Tip:
Highlight text to annotate it
X
Narrator: Dr. Linda Barbour has special expertise and
research interests in the medical problems of pregnancy.
She has a masters of science in public health.
She's past president of the North American Society of
Obstetric Medicine.
We're indebted to her for chairing the HealthTeamWorks
in Colorado Department of Public Health and Environment
Guidelines for the Management of Gestational Diabetes.
She serves as the medical director for both the High
Risk Obstetrics Clinic and the Obstetric Diabetic Clinic, and
she's a national leader in developing clinical guidelines
for medical complications in pregnancy, as well as the
co-editor of the textbook Medical Care of
the Pregnant Patient.
Welcome.
Dr. Linda Barbour: Well, thank you for that kind
introduction, and I want to thank all the organizers--
especially Linda Archer, who could not be here, Mandy,
Thea, and Emily--
to get to speak to you about some of the controversies of
the Institute of Medicine guidelines.
And I'm going to warn you at the onset that this is going
to be a little data dense.
I felt this was important to make sure that I gave you all
of the data out there.
So if we come up with a conclusion that there should
be a deviation from those guidelines, at least you are
armed with the data that justifies that.
So I know this seems punitive after you've just had lunch to
hit you with all this data.
But I believe that the slides will be available as a PDF, so
after the presentation is over, you can go through them
and have them to support whatever stance you end up
taking at the end of this.
So in the next 55 minutes, what I'd like to do is give
you a little bit of the rationale behind the 1990
guidelines.
We'll also explore some of the observations in obstetric
medicine that really necessitated the IOM to
rethink those guidelines and to change them in 2009.
I'll highlight one of the driving forces that really
made folks rethink about these guidelines, and that was an
appreciation that the intrauterine environment might
not only cause some adverse outcomes early on, but
actually contributed to our pediatric obesity epidemic.
Because that ended up being a very important force that
changed the guidelines.
There was also a recognition that, unfortunately, in every
pregnancy, women were gaining a certain amount of weight and
then not losing it.
And so that women were going into their subsequent
pregnancy weighing much more than their previous pregnancy.
And that realization also was a driving force in looking at
the gestational weight gain recommendations.
And you would think that you could probably just look at
the physiology of pregnancy, what energy requirements are
during pregnancy, to come up with what would be appropriate
gestational weight gain.
And we'll actually review a little bit of that data,
because I think it's interesting.
And then finally, we'll look at those 2009 guidelines.
We'll decide whether we really think they are different.
And then I'm going to ask you to be patient with about 15
slides that are very data-driven that really
challenge the recommendations that the IOM came up with,
especially in women who are overweight or obese.
We'll wind up talking a little bit about what can be done to
try and achieve these guidelines in our practice.
Are there interventions that actually work?
And then I'll give you my final two cents' worth about
how, at least, I would interpret all this data.
So in the 1930s, it's very interesting.
It was recommended that all women gain about 15 pounds
irrespective of their weight.
A lot of women were smoking at this time, and they were doing
that intentionally to make sure that they didn't gain
more than those 15 pounds.
And then in the 1970s, it was appreciated that maybe this
15-pound weight limit was a little bit too restrictive.
Maybe smoking was also not a great idea.
And so, there was a new guideline that all women
should gain about 20 to 27 pounds.
And then after 1970, there was an increasing recognition that
all women were not the same BMI, as we started
seeing this BMI splay.
And that perhaps one weight gain size was really not the
best way to approach this.
So in 1990, for the first time, the IOM looked at
gestational weight gain recommendations as a function
of maternal BMI.
But what was their most important focus was preventing
small-for-gestational-age babies.
Because at that time, there was an increasing number of
small-for-gestational-age babies that were surviving,
that neonatal intensive care unit costs of these babies was
extraordinary, and that was really thought to be the main
focus of the development of the 1990 guidelines--
to try and prevent that.
And when you look at when the IOM guidelines were actually
put forth in 1990, and you look at what was going on in
terms of maternal weight gain, you can see that they looked
at data in the '80s and in the '70s, and at that time there
were as many mothers who were underweight as overweight.
And there were very, very few women coming into pregnancy
with actual obesity.
That has completely changed.
And as you can see, as time went on, that more and more
women were becoming overweight going into pregnancy.
But in 1990, that was really not yet the case, and so the
guidelines came out for the first time, again, dependent
on BMI that you see in this following slide.
Underweight, 28 to 40 pounds.
Normal weight, 25 to 35.
Overweight, 15 to 25.
And then obese, BMI greater than 30, at least 15.
There was not an upper limit to that recommendation.
What was not done is there was no distinction between obese,
severely obese, or morbidly obese.
Again, because there really weren't very many obese women
in 1990, anyway.
And then, something happened after 1990.
As you can tell on this graph, there was all of a sudden a
striking increase in obesity in pregnancy that happened in
the '90s, early 2000.
And by mid-2005, basically 30 percent of all pregnant women
were obese, compared to only 10 percent prior to those 1990
guidelines.
And in fact, in some populations, especially in
non-Hispanic blacks, up to 50 percent of women were obese
entering their pregnancy.
And when you look at just kind of the United States
statistics, around 2005 you can see that two-thirds of the
population of women of childbearing age were either
overweight or obese, radically different than what was seen
before those 1990 guidelines.
And so, there was this appreciation that somehow
after 1990, there was this acceleration in problems with
obesity and overweight, both in mothers
as well as in children.
And if we look at the data even after 1999 in kids, what
were left in 2008 is 17 percent of children are now
defined as obese, which is greater than the 95th
percentile for height.
While obesity was being recognized as a major problem
in obstetrics, and there was some U.K. data showing that
although in the U.K. in 2000, only 15 percent of their
population was obese, unlike our 30 percent, it actually
accounted for 35 percent of all the maternal deaths.
And it was finally recognized by ACOG as actually the
leading cause for excess maternal morbidity and
mortality, as well as neonatal morbidity and mortality.
It was estimated to increase the cost of prenatal care by
sixteenfold, and it was realized that obesity had
actually doubled.
And I think many of you are very aware of all the risks of
obesity, and this is not what this talk is about.
But I laid this out on the slide for you in terms of the
most common medical and obstetric complications of
obesity with a very good reference.
And obviously, this not only affects the mother, but in
fact, obesity markedly increases the risk of
miscarriage and major malformation, and quadruples
perinatal mortality in these babies.
And so again, this was being recognized as probably the
biggest threat to health care of moms.
After 1990, as I alluded to, there was this increase in
large-for-gestational-age babies much more than
small-for-gestational-age babies, which had really been
the focus previously of IOM.
And no matter what country you looked at, there was this
increase in birth weight.
And in fact, in Boston between the years of 1980 and 2000,
about a 20-year period, infant obesity had almost doubled.
Well, at the same time, the Barker Hypothesis was gaining
a lot of momentum.
That in fact, we knew that low-birth-weight babies were
at risk for metabolic syndrome.
But at the time, there was increasing research looking at
the opposite end of the spectrum.
That in fact, large-for-gestational-age
babies were at every bit of risk for cardiovascular
morbidity/mortality, as well as obesity and metabolic
syndrome later in life.
And now, this LGA population was much greater than the SGA
population.
And so there began to be a focus on these
large-for-gestational-age babies.
And when you try to determine what makes a baby bigger than
normal, it's not, unfortunately, proportionate
increase in lean mass and fat mass.
In fact, the difference in birth weight was all due to an
increase in fat mass.
And Catalano, I think, really has to be credited as one of
the first investigators to look at body composition of
babies rather than just birth weight.
And he found out that indeed, babies born to mothers with
obese had about the same lean mass, and what they differed
in was fat mass.
And when Dr. Catalano from the Cleveland Clinic looked at
what was the biggest predictor of babies being born obese
with this excess fat mass, he found that actually pregravid
weight was the most predictive for babies born with increased
fat mass, as you can see, with a P value of less than 0.001.
Maternal weight gain was also important, but was a little
blunted to the effect compared to maternal
obesity entering pregnancy.
And then, some data that was actually available to the IOM
in 1990, but wasn't appreciated until after that
because there just weren't very many overweight or obese
mothers, is that although there was a clear relationship
between maternal weight gain and birth weight in
underweight, in normal weight women, there was almost no
relationship in obese women.
That is, obese women didn't need to gain any weight to
have an infant of normal size.
And there was only that need to gain weight to have an
infant with a good birth weight in ideal weight,
underweight, and a little bit in the modestly overweight
population.
So in 2007, it was clear that these guidelines
needed to be addressed.
And in part, that was due to the fact that there was a
recognition that 38 percent of normal weight, 63 percent of
overweight, and 46 percent of obese women gained more than
the 1990 recommendations.
Also that now in 2007, we were sitting with two-thirds of our
maternal population overweight compared to only
one-third in 1990.
There was this increase in LGA much more rapidly than SGA.
And now it seemed like small-for-gestational-age
babies were no longer due to nutritional deficiency in
moms, but actually most of them could be explained by
medical problems that would cause placental insufficiency.
So the mothers giving birth to SGA babies were not the ones
that weren't gaining enough weight, but in fact, these SGA
babies were due to maternal complications, such as chronic
hypertension, renal disease, advanced diabetes,
rheumatologic disease, that caused placental insufficiency
that caused them to be small for gestational age, not
because mothers were not eating enough.
There was also an appreciation that gestational diabetes,
preeclampsia, and C-section rates were increasing and very
much related to maternal BMI, and increasing appreciation of
the intrauterine influence on the
pediatric obesity epidemic.
And so that maybe eating for two was no longer
such a great idea.
Well, soon after 1990 publication of the IOM
guidelines, a recognition of this very important
intrauterine environment and its impact on long-term
disease and health in children were recognized.
And in fact, that set the stage for the developmental
origins of disease researchers to start.
And it's interesting that this appreciation of how important
the intrauterine environment was in later chronic health to
the baby, it was as early as 1990.
And soon after that, there was more data suggesting that, in
fact, if you looked at what caused obesity in a
four-year-old, the strongest predictor of obesity is
whether mother was obese coming into the pregnancy.
And the second-most-potent predictor was if the
baby was born big.
And so, this data also was very supportive of the fact
that obesity and being born large set this child up later
to struggle with obesity as a child.
And then another article came out that really made people
rethink the contribution of gestational diabetes in
causing women to have babies that were too big.
Because it found, in fact, that what was more predictive
of a baby ending up with metabolic syndrome as a
six-year-old was not whether their mother had gestational
diabetes, but whether they were born big and if their
mother had obesity.
So again, with well-controlled gestational diabetes, it
actually was not as much of a predictor as obesity in mother
and being born big.
And Pat Catalano now, at about 2007, and about the time that
the 2009 guidelines were about to be launched, showed his
data, which now followed these kids up to nine years of age
and looked at their body composition as nine-year-olds,
and looked back to see what in pregnancy predicted obesity
and excess body fat in a nine-year-old.
And these graphs on the bottom show you that, No.
1, again, birth weight really doesn't relate very well to
child weight at nine years old.
Because it's not how much you weigh, it's your body
composition.
What really predicted child obesity and excess fat by DXA
in these nine-year-old children was being born with
excess fat as a baby.
And the No.
1 predictor of these offspring growing up to have excess fat
was in fact maternal obesity.
And it explained 18 percent of the variance in childhood
adiposity and markedly increased the risk factor of
obesity later on.
And this is his data.
As you can see, just in this little red square, that it
turned out that pregravid BMI was the most potent predictor
of being in the upper tertile of fat at nine years of age,
and was even much greater of an effect than gestational
weight gain.
And these kiddos at nine years old who were in this higher
tertile had higher systolic blood pressure, insulin
resistance, triglycerides and lower HDL.
So the fetal origins hypothesis sustained a great
increase in enthusiasm.
Instead of only looking at babies who were born small and
looking at their outcomes, it started recognizing that
babies who were born big, and in women in which there were
excess nutrients, in which there was obesity, excess
triglycerides, glucose, that these babies were also at a
very high risk of developing metabolic
problems later in life.
And probably one of the most compelling data that really
shook people up was data in non-human primates, so in
monkeys who have the same placenta as we do.
And it was shown that, in fact, if you feed these mother
monkeys a high-fat diet, not only did you cause them to
have bigger organs, more fat, but in fact you could change
their appetite regulation in their brain, and you could
change their energy expenditure.
So what these little baby monkeys wanted to do after
they were born is eat and sit, very unlike the other monkeys.
And now we are 20 years later from that Newsweek magazine,
and we finally have a little bit of a handle on how the
intrauterine environment might impact the developing fetus,
to put that fetus at increased risk for metabolic problems
and obesity later in life.
And that field is called epigenetics, where now we
understand that excess fuels--
glucose, lipids, inflammatory cytokines, a number of
different things--
actually change gene expression, actually change
the way the DNA is expressed.
And this is how this sets up these kids later in life to be
more prone to develop obesity and metabolic problems.
And lastly, there was an appreciation that, again,
maternal BMI was probably the biggest risk factor in
childhood obesity, that 25 percent of obese kids at age
four already have impaired glucose tolerance.
And if you were an obese newborn, you were up to nine
times more likely to be obese as an adult.
So that was some of the driving forces looking at this
whole issue of intrauterine programming.
That again, excess weight, excess nutrients can really
set up this kid to have an increased risk of obesity
later in life.
But another driving force to change the IOM guidelines was
the appreciation that women were not losing the weight
they gained in pregnancy.
In fact, they were going into the next pregnancy at even a
higher BMI.
And there was data again by our friend Pat Catalano that
60 percent of previously normal weight gravidas became
overweight with their subsequent pregnancies because
they never lost that weight.
And this figure really demonstrates that, especially
in women who are obese, the weight that they gain is never
lost. And so they never get back to their
pre-pregnancy weight.
And in fact, the biggest predictor of holding on to
your weight at either 15 years old after you had your baby,
or even up to 21 years old after you had your baby, was
how much you gained in that pregnancy.
And women who gained more than the IOM recommendations were
at a very high risk 8 years, to 15 years, to 21 years later
of being overweight or obese.
And this again shows that the more you gain in pregnancy,
the more likely you are to be overweight a year later.
And especially women who were black had even a higher weight
retention compared to white or Hispanic women in terms of
their weight gain in pregnancy.
Well, before we reexamine further data with the
guidelines, you would think that you could just look at
the physiology of pregnancy and figure out how many
calories a pregnant woman needs to gain to have a baby
that's appropriate size.
And appropriate size is definitely not this 19 pound,
2 ounce baby that is kind of pushing out a one-year-old
that we're really talking about.
And it turns out when you look at the energy costs of
pregnancy, it's a little bit of a surprise.
It's not so much making this baby, this seven-pound baby,
but the energy costs actually have to do with maintaining
that pregnancy over nine months, with the increased
basal metabolic rate in pregnancy that increases due
to that weight that you're dragging
around for nine months.
So when you look typically at, for example, in England, a
woman on average gains about 22 to
28 pounds in a pregnancy.
And so, from this it was recommended that women take in
an extra 300 kilocalories a day, or 77,000 kilocalories
during the pregnancy.
And when you look at where those kilocalories are going,
only 5,000 of that is going to make that baby.
Half of that, 35,000 calories, is going to putting on the
extra fat that mother puts on during pregnancy.
And the other 35,000 calories actually goes into just
maintaining the new tissue, maintaining the pregnancy due
to the increased basal metabolic rate now that mother
has during those nine months.
So if you just look at the baby, the conceptus, and the
energy expenditure that it takes to maintain that
pregnancy, instead of 77,000 calories, or 300 a day, it
takes about 41,000, or an extra 160 kilocalories a day.
And a slightly different way of looking at it is you can
look at where weight gain goes.
So there are what are called obligate weight gain for the
baby, for the placenta, for the increase in uterus size,
increase in breast tissue, the amniotic fluid, and the blood
volume increase.
And if you look at those obligate weight gains, that
comes out to be about 17 pounds.
But when you factor in the excess fat that mother gains,
as well some of the extra water in edema mother gains,
then that comes up to be more like 28 pounds.
So obligate weight gain that accounts for the baby and then
all the tissues that need to increase to support that baby
is about 17 pounds, or 225 kilocalories a day.
And it's not until you factor in the excess fat and edema
that you get to this 375 kilocalories a day.
And lastly, one other way of really looking at this is
looking at how much weight do women gain
in different countries.
Well, in Sweden, the average woman gains 41 pounds.
And so, she has to take in 540 extra calories a day.
And when you look at where those calories are going,
75,000 are going for fat.
So that white bar is the baby's normal size, and what
accounts for all that extra weight is all that fat that
that Swedish woman is putting on during her pregnancy.
You look in England, where the average weight gain was about
22 pounds, baby is the same size, but now the women are
putting on half that much fat.
So only 36,000 calories are going for that.
And you look at Thailand, where women are really not
putting on much fat at all, and they only gain 12 pounds,
pretty much all going to the baby, as well as what it needs
to support that pregnancy.
And then if you look at countries in which there is
nutrient deficiency, mothers actually burn their own fat
and are actually are in a caloric
deficit to maintain pregnancy.
So in 2000, the IOM clearly realized that they needed to
re-look at all this data.
And one of the things that they looked at is they wanted
to figure out what the determinants
of weight gain were.
And they realized that thin women tend to gain weight
earlier and gain more fat than obese women.
And that overweight women and obese women did not gain more
than lean women, but gained more than the IOM guidelines.
They also realized that there were ethnicity differences in
weight gain, especially in Hispanic women and black women
who tend to gain more than Caucasian women.
Women of lower education gain more.
Younger adolescents gain more.
Primigravidas had more weight gain, but they actually have a
higher risk for small-for-gestational-age
babies, probably due to the increased risk of preeclampsia
in primigravidas.
And then, of course, smokers have very little weight gain.
But it's interesting that although they have smaller
babies, if you look at the distribution of those babies,
they actually have more fat than they do lean body mass.
So in 2009, the IOM came up with new recommendations, and
those are shown for you.
And if you recall what those recommendations were in 1990,
there is no difference in any single category with the
exception of obesity.
And the only difference was now, instead of saying that
women should gain at least 15 pounds, they put a lid to it
and they said you should gain anywhere from 11 to 20 pounds.
And if you recall, that's kind of that obligate weight gain
of pregnancy, right around 17 pounds.
In addition there was no distinction
on grades of obesity.
So women who had a BMI of 35 or 40 or 45 were told to still
gain that obligate 11 to 20 pounds.
And they did not change any of their
recommendations in terms of twins.
So why so little change in the guidelines?
Well, this is a nice editorial done by Dr. Rasmussen, who was
actually on the committee, published in OB/GYN in 2010.
And she supports the IOM's rationale for not changing the
guidelines with the following: that they really wanted to
balance the risks of low- versus high-gestational weight
gain and to do no harm.
They also appreciated that even more potent than
gestational weight gain in causing babies to be born with
excess fat was maternal BMI.
So they wanted practitioners to really focus on trying to
get obese women to lose weight before they got pregnant.
They also realized that, unfortunately, women were
already, even with the 1990 guidelines, the vast majority
were gaining more than those guidelines.
So they ratcheted down those weight gain levels even less.
Almost everyone would be certainly gaining more weight
than recommended.
And so to just to try and get women to gain within the 1990
guidelines, which were pretty much the same as the 2009
guidelines, would be a big benefit.
They also weren't sure whether they should weigh
large-for-gestational-age babies the same way as
small-for-gestational-age babies.
Should SGA babies, should that be even more important to
prevent than
large-for-gestational-age babies?
One of the biggest criticisms in their data analysis, which
I'll show you, they did not include preeclampsia or
gestational diabetes as important endpoints to try and
prevent with excessive weight gain.
They said that those were confounded by a lot of
different things.
Yet, they included emergency Cesarean section as an
endpoint, and I think all of us who practice obstetrics
know that there are many things other than just
gestational weight gain that make you decide if you're
going to do an emergency Cesarean section on a patient.
So that was unclear why they threw out all the studies that
looked at preeclampsia and gestational diabetes outcomes.
And then they said there really was inadequate data to
really focus in on that group with a BMI of greater than 35,
so they went ahead and just used the same weight gain
guidelines for them as they did the BMI of 30.
Well, soon after that was published, there were a
plethora of oppositions and editorials and comments about
why the weight gain guidelines really did not
significantly change.
And this is probably one of the best ones published in
Obstetrics & Gynecology by Charlie Lockwood and his team
in Utah, who basically came out and said, they should have
included preeclampsia, gestational diabetes.
They did not stratify for more severe levels of obesity.
And they really didn't fairly factor in
postpartum weight retention.
And again, Kathleen Rasmussen, I gave you that reference.
She put forth the rationale, and I'm going to show you the
rationale right now, in terms of how IOM came up
with what they did.
So the 2000 rationale for the IOM guidelines was based on a
woman being a primigravida, being age 25 to 29, being a
non-smoker, high social status, and no exercise.
The only outcomes IOM looked at in arriving for their
weight gain recommendations was small-for-gestational-age
babies-- which they wanted to minimize--
large-for-gestational-age babies, emergency Cesarean
section, and postpartum weight retention they did factor in.
They did not look at preeclampsia, gestational
diabetes, any other factors.
And so you can see where they kind of targeted
their weight gain.
And it actually made a fair amount of sense, I think, for
the underweight and the normal weight.
But it's a little interesting where they drew their
thresholds and where they targeted women who are obese
or overweight.
Because it's not easy to track these lines, but the lines
that are coming up high towards the right is
postpartum weight retention.
The lines that are kind of going down are usually small
for gestational age.
But you can see that in the obese category and extremely
obese category, small for gestational age was already
less than 10 percent.
And why they didn't shift their threshold all the way to
the left to no weight gain, because really, there was no
increase in small-for-gestational-age and
you could blunt the increase in LGA, emergency C-section,
and postpartum weight gain by doing so, wasn't clear.
Why didn't they shift that to no weight gain?
And what they said is that they did admit that there was
a fair amount of data suggesting that you did not
need to gain the obligatory 17 pounds that
we just spoke about.
But the data was limited, and they didn't feel like they
could actually come out with a statement that no weight gain
was acceptable.
And then there were a number of studies that suggested that
weight loss was actually beneficial, and they said,
"Well, we don't know long-term neurologic outcomes in terms
of ketones," so they certainly weren't ready to embrace
weight loss.
Well, in just the next five to 10 minutes, I want to give you
really the important data that I think you'll need if you
decide also to deviate a bit from the IOM guidelines.
And I'm going to just kind of give you the bottom lines, but
I've shown you all the data, so you can go back and take a
look at this.
One of the most compelling data sets was by Oken in 2007.
And he looked at all the data from Harvard Project Viva of a
thousand mother-child pairs.
And what he looked at is gestational weight gain and
the correlation in childhood obesity at the age of 3 years.
And what he found, that if women gained, no matter what
their BMI was, if they gained more than the IOM weight
guidelines, then there was a fourfold increase in these
3-year-olds being obese.
But interestingly, if they gained according to the
guidelines, there was a 3.7 increased risk of these babies
being an obese 3-year-old.
And if they gained an "inadequate," amount, there
was no increased risk.
And of the women who gained an inadequate amount, there was
not an increased risk for
small-for-gestational-age babies.
So it was really one of the first to really challenge
these guidelines.
And then DeVader looked at the Missouri birth certificate
data and looked at normal-weight women.
And this time, instead of just looking at SGA, LGA,
postpartum weight retention, and emergency C-section, he
looked at a number of outcomes that he wanted to minimize,
and then try and find the best weight gain to minimize
preeclampsia, cephalopelvic disproportions, shoulder
dystocia, failed induction, C-sections, and
LGA, as well as SGA.
And what he found in normal-weight individuals,
that if they gain less than 25 pounds, everything was
benefited except small increase in SGA.
If they gained more than 35 pounds, they had more of all
of these adverse outcomes, but of course SGA was
a little bit lower.
So he came out that for normal-weight women, probably
25 pounds, was an ideal amount to gain.
And this shows his data again, that if you gain less than 25
pounds, that's good for every outcome except for SGA.
You certainly decrease LGA, failed induction, C-section,
but you do slightly increase SGA.
More than 35 pounds, all those bad, adverse outcomes
increase, except for, of course,
small-for-gestational-age baby.
Well, Cedergren really challenged the data.
He looked at the Swedish medical birth registry of
300,000 singletons, and he looked at
every single BMI category.
And instead, again, of just looking at SGA, LGA,
C-section, and postpartum weight retention, he said,
"I'm going to look at the weight gain that is optimal in
each category that decreases the maternal outcomes and the
fetal outcomes we think are absolutely the worst." So he
did a composite outcome.
And he said, "What weight gain is ideal to prevent
preeclampsia, postpartum hemorrhage, thromboembolism,
shoulder dystocia, still birth, perinatal death, low
Apgars, as well as SGA and LGA?" And what he came up with
was incredibly lower weight gain
recommendations than the IOM.
So it's amazing that, even in underweight women, he said,
they should only gain 9 to 22 pounds.
A normal weight, 5 to 22, compared to the IOM.
And then when you get into overweight or obese, 0 to 20
for overweight and 0 to 13 for obese.
And this, again, is just the data that supports that 0- to
about a 9-kilogram weight gain for overweight, and 0- to
about a 5-kilogram weight gain for obese.
And then Kiel said, "All right, well, we'll look at the
Missouri birth certificate data," and he focused on women
with a BMI greater than 30.
He just looked at preeclampsia, Cesarean
section, SGA, and LGA.
He says, "What is the best weight gain to minimize SGA as
well as LGA?" so kind of where those lines cross in
women who are obese.
And he found that in women who had a BMI of about 30, 15
pounds was probably OK.
They could probably gain no weight.
You can probably see that at zero, there really isn't any
significant difference.
But clearly, in women with a BMI of 35 or greater, you
could minimize SGA with them having a 0- to 9-pound weight
gain, and in fact, if they had a BMI greater than 40, a
weight loss of 0 to 9 pounds was optimal
without increasing SGA.
And then, Potti decided to look at the New Jersey PRAMS
database, and say, "I'm going to apply Cedergren
recommendations versus the IOM recommendations, and see who
wins out on the best outcomes." And what he found
out is that with the Cedergren recommendations, he could
decrease macrosomia and C-section rates.
But there was a slightly higher rate of preterm
delivery, low birth weight, and NICU admissions.
And so he recommended somewhere between the
Cedergren and the IOM recommendations.
And we're almost through this data.
Another large cohort that I think is very important to
present to you was a varying cohort of 188,000 babies.
And this investigator, again, looked at where you can
minimize the risk of both LGA and SGA.
And what she found in that cohort that's called the joint
predicted risk, trying to keep both LGA and SGA less than 20
percent, that unlike the IOM guidelines, for overweight, it
was minus 15 pounds to 26, and for obese it was
minus 33 to plus 4.
And if you really felt compelled to make sure that
SGA never exceeded 10 percent, then again for overweight it
was 0 to 26, and obese, minus 15 to plus 4.
So fortunately, there's a really nice review out there
that tries to look at all of this data that I just hit you
over the head with, which was a meta-analysis and review in
American Journal of Obstetrics & Gynecology in 2009.
And they took the 35 highest-quality studies drawn
from the report conducted for the Agency for Healthcare
Research and Quality.
And they said that if you look at all that data up to 2009,
there is strong support between excessive gestational
weight gain and
large-for-gestational-age babies.
No question about it.
However, there's only strong support between inadequate
weight gain in small-for-gestational-age
babies in normal weight or underweight women.
There's no relationship between inadequate weight gain
and small-for-gestational-age babies and
overweight or obese women.
Because they don't have SGA babies to begin with.
There was support between gestational weight gain and
postpartum weight retention, and they came out with a
pretty strong statement, saying that overweight and
obese women who gained below the IOM recommendations do not
have a higher risk for
small-for-gestational-age babies.
And they felt that this report should really be used by the
IOM and they re-examine their guidelines in the future.
And then lastly, I just want to show you just three studies
that came out after that big analysis, so
that you'll have them.
This, again, was a look at all the babies born in the
Pregnancy Nutrition Surveillance
System, 122,000 babies.
And they looked at women with a BMI greater than 30.
And what they saw was something similar to what
we've been seeing over and over again, that the best way
to avoid both SGA and LGA for Class 1 obesity, that's a BMI
of 30, is anywhere from about 0 to 5 kilos.
But for Class 2 and 3, you really didn't need any weight
gain, and it was even acceptable to
lose up to 5 kilos.
Oken, who championed, really, the Harvard Project Viva that
we talked about earlier, decided to take his 2,000
mother-child pairs and not only look at the best weight
gain that minimized SGA and LGA, but also that prevented
childhood obesity, as well as weight retention.
And he came out that in normal-weight women, 25 pounds
was probably the best. But in overweight women, a weight
loss of 3 pounds was the best. In obese women, a weight loss
of 17 pounds decreased postpartum weight retention,
childhood obesity, minimized SGA, and also minimized LGA
and preterm birth.
And then, one last study of 5,000 children in the National
Longitudinal Survey of Youth.
I give this to you again just so you'll have all the data
that's been published up to 2011.
They looked at optimal weight gain based on, again,
childhood overweight, as well as SGA, LGA.
And they came up that the optimal gestational weight
gain for obese women was 0 to 5 kilograms.
And I promise you this is the last data set I'm going to
show you, and I think this is pretty interesting, because
it's the only data set that now looks at optimal
gestational weight gain in 9-year-old obesity, like Pat
Catalano tried to do.
But in addition to what Pat did, they looked at
gestational weight gain and the influence of not only
obesity at 9 years by DXA, but also all these other
biomarkers that are very, very bad in children that certainly
predict metabolic syndrome.
And he found out that gestational weight gain
greater than the IOM recommendations in 2009
markedly increased the risk of obesity at 9 years old, as
well as leptin, systolic blood pressure, CRP, IL-6, and
decreased HDL--
all these bad biomarkers.
But if you gained less than what the 2009 recommendations
put forth, you would decrease that adiposity in nine years,
and they wouldn't have any of those bad markers.
And lastly, the champion of follow-up is the Southampton
U.K. Project, where they looked at moms who were
pregnant in the '60s, and they followed these kids
up until age 30.
And they found that pregravid BMI, that we've heard about,
as well as high gestational weight gain, were the
strongest predictors of these 30-year-olds being obese.
So before we wind up, and then try and come to our senses and
come up with what we think makes sense in terms of the
IOM recommendations, I just want to spend literally a
couple minutes on, in fact, is there anything that we can do
practically to minimize excess weight gain in pregnancy?
Are there any trials that actually show that
anything we do works?
And what I can tell you now, there used to be a myth that
exercise caused babies to be too small, and
that really is a myth.
There is now a lot of data showing that exercise
decreases the risk of gestational diabetes,
preeclampsia.
ACOG recommends that women every single day increase
their physical activity by 30 minutes.
And in fact, there is no increase in miscarriage rate
in women who exercise.
There's no difference in birth weight in terms of growth
restriction, except for in marathon athletes who do
endurance exercise into their third trimester.
And I don't even know how that would be possible.
But I guess there's a few women out there.
And that again, there's no increase in preterm labor,
except for if you're doing endurance exercise in your
third trimester of pregnancy.
Unfortunately, there are only four randomized controlled
trials out there--
I've put them all on this slide for you--
looking at whether interventions that include
diet, exercise, trying to reinforce appropriate weight
gain recommendations make a difference.
And, sadly, in only one of them was the intervention
clearly successful.
And in that, they took 50 women with a BMI of 29, so
overweight to obese.
And basically, it took 10 one-hour visits throughout
pregnancy to help try and get them to minimize
excess weight gain.
And so, with 10 hours of intervention, there was a
difference in the women in the intervention group versus the
women who were not.
But in other ones, there was either a modest or no benefit.
So it really takes more than just giving a woman a brochure
and telling her to exercise and eat right.
And then lastly, how good are we at getting women to lose
weight postpartum?
Well, we're terrible.
And one of the reasons this has been so unsuccessful is
some of these barriers I've put up.
Clearly, breastfeeding helps women lose weight.
There's no question about it.
But these women are also dealing with sleep
deprivation.
And very sadly, as you probably know, when you're
tired-- like you probably are right now--
you need to eat.
You feel like you need to eat to stay awake.
And that's actually mediated through your appetite center.
When you are sleep-deprived, ghrelin, which is the appetite
stimulant, goes up.
And leptin, which suppresses your appetite, goes down.
And how many postpartum women are sleep-deprived?
There's certainly time constraints.
They don't have time for exercise.
For some reason, women who bottle feed eat a higher fat
and carbohydrate diet than women who breastfeed.
And then of course, there's the influence of postpartum
depression that occurs 10 to 15 percent, and most women
tend to overeat when they're depressed.
So in drawing conclusions over this ride of data, I think we
can truly safely say the following without
going out on a limb.
Most women do not follow the IOM guidelines.
Fifty percent gain more.
It's clear that excess weight gain correlates with
preeclampsia, gestational diabetes, C-section, and
postpartum weight retention.
Birth weight and small-for-gestational-age
babies are related only to weight gain in underweight and
normal-weight women.
There is no association with small-for-gestational-age
babies and inadequate birth weight in
overweight or obese women.
So it's a factor when thinking about normal-weight women and
underweight, but does not seem to be a factor in our
overweight or obese population.
I think future studies are really going to need to
stratify smoking status, because that's the most potent
predictor of
small-for-gestational-age babies.
Obese women, especially with BMIs greater than 35, there's
really no data that suggests they need to gain weight, and
all the data would suggest they don't.
There's increasing data, as we've talked about, that
infants born with excess adiposity have an increased
risk of childhood obesity and glucose intolerance by this
fetal programming that we spoke about.
Maternal BMI is probably the greatest risk for that.
High fat diet plays a role.
And I don't want to underestimate the importance
of stressing a healthy diet in these women, not just not
gaining too much weight.
Because it looks like glucose, but even more so, high free
fatty acids and triglycerides causes babies to accrete
excess fat, even maybe more so than glucose.
Daily moderate exercise certainly appears safe, and is
likely beneficial if we can get women to do it.
And I think there's no question that the IOM needs to
re-examine recommendations for overweight and obese women and
stratify grades of obesity.
So now, I'll give you my two cents' worth in trying to
really synthesize the data and come up with something that I
feel we're not on too much of a limb about, that we can feel
fairly comfortable about.
No.
1: Yes, lose weight before pregnancy.
Certainly that needs to be an emphasis.
Unfortunately, there are really no preconception
programs out there to do that.
But pregravid BMI is critical.
No.
2: Stress a healthy diet.
Decrease fat and simple carbs.
Because as we've talked about--
I didn't show you the data for this--
but you can really create an obesity phenotype by which you
feed a mother, and you can change appetite regulation,
and even energy expenditure.
Daily moderate activity is so essential, and we know in our
GD population, it helps women even from having to take
medications if they'll just take a walk after they eat.
And in terms of weight gain, what is my read on it?
Well, I think what I would do is in the lower-weight groups
up to overweight to strive for the lower end of the IOM
recommendations.
I'm not too worried about women with a BMI less than 20.
I'm not too worried about their
weight gain in pregnancy.
Most of them don't gain too much weight, so I think the
IOM guidelines are just fine for that weight group.
In terms of normal-weight women, I think there is a lot
of data suggesting that targeting 25 pounds, instead
of 25 to 35, makes sense.
That extra 10 pounds certainly increases the risk for LGA,
postpartum weight retention, so I think it makes more sense
to target the lower limit of the IOM guidelines, which
would be 25 pounds for a normal-weight woman.
She certainly will not have an increased risk of SGA there.
For overweight women, I would target, once again, the lower
limit of the range.
Instead of 15 to 25, I would recommend 15.
Again, no data that would suggest that you're going to
increase SGA, and only data to suggest that you're going to
improve LGA, C-section, preeclampsia, postpartum
weight retention.
And now, what about this obese group?
I think there's actually a lot of data saying that obese
women don't need to gain any weight.
But I think if we're conservative, we can at least
say to tell these women not to gain more than 10 pounds.
IOM says at least 11, but that's kind
of an awkward number.
So I tell women don't gain more than 10 pounds, and I
think there's actually a fair amount of data they don't need
to gain any.
In terms of BMI greater than 35, every study that I can see
shows that no weight gain is needed.
Some studies show that these women do even
better losing weight.
I'm not ready to propose that, but I really don't think
there's any data that shows that women with a BMI greater
than 35 need to gain any weight.
And obviously, stress the effect of too much weight gain
on their postpartum weight retention at a year.
So to sum up and stay within this 55 minutes, for the first
time, we are looking at the possibility that our offspring
face a 10- to 20-year shorter lifespan than us.
In Southern California, a third of kids are obese, and
they are developing health problems in their 20s that we
typically see in 40- to 60-year-olds.
And so I would submit to you that what is certainly
feeding, if you will excuse the pun, the pediatric obesity
epidemic certainly has to do with a lot of variables,
including our genetics.
But the intrauterine environment is very important.
Pregravid BMI is incredibly important.
Trying to get women to lose weight before pregnancy cannot
be emphasized enough.
But in addition to that, insulin resistance, excess
glucose, lipids, a high-fat diet, and certainly
gestational weight gain play a role in setting these kids up
later to be overweight.
And then, of course, the postnatal environment is huge.
But in addition to just trying to get kids to exercise and
not eat so much, there are some very recent findings that
soon after birth it's really important not to overfeed
small-for-gestational-age babies.
And it's incredibly important not to overfeed even
normal-size babies the first two years of life.
Because rapid weight gain in the first two years of life of
even an average-size baby gives them a five- to tenfold
increased chance of obesity at 12 years.
Those are times when they're really
proliferating their fat cells.
This is not the time you want them to
proliferate them even more.
And there is increasing data now, very elegantly done, in
sibling pairs that breastfeeding markedly
decreases obesity when one of the sibling pairs was
breastfed and the other wasn't.
And so this really shows the power of breastfeeding being
able to tease out the genetics and the postnatal environment.
So for those of you still conscious after that data
overload, I want to thank you for your attention.
Narrator: Great.
We will look on the sidebar here to see what questions we
have. And then, if you need to unmute your phone, press *6.
That's *6.
And then ask a question into the phone.
But I'll open this up first.
First question: Would you please comment on distribution
of the weight gain throughout the pregnancy?
What amount of women who lose a significant amount of weight
in the first trimester and then gain rapidly toward the
end of the pregnancy?
Dr. Linda Barbour: That's an excellent question.
There's actually data that I did not show you showing that
you really don't need to increase those calories much
at all in the first trimester.
No weight gain in the first trimester is probably OK.
That baby is just a peanut.
We don't like weight loss because of ketosis, and we're
still not exactly sure about ketosis.
And as I briefly mentioned, thin women tend to put their
weight on earlier.
Obese women tend to put it on later.
Certainly, early in pregnancy, women are
putting down fat stores.
Just their physiology is that insulin, more sensitive state,
where they put on fat, and later they actually become
resistant, and so those fuels go to the baby.
So I would say that it's just important to go for that
target, and realize that the first trimester of pregnancy,
it's really not important to be trying to gain weight.
And so that 15-pound weight gain that you might recommend
for overweight women can certainly start up in the
second and third trimester.
Narrator: Next question is what do you consider LGA?
I've seen infant weight of 8.5 as a predictor of IGT.
Dr. Linda Barbour: So, LGA by definition is babies that are
in the 90th percentile of weight for
their gestational age.
And so, by definition, you would think that that means
that only 10 percent of babies can be LGA, because of the
90th percentile.
But they came up with those large-for-gestational-age
definitions based on older data before these
babies got so big.
So they've taken data in the '70s and '80s of really what
an LGA baby and an SGA baby is.
And so now, what they look at is, again, for gestational
age, is that baby greater than the 90th percentile of
what it should be?
And 8.5, again, it depends on when you're born.
8.5, if you're 37 weeks, you're a big baby, and you're
an LGA baby, and you're absolutely right.
That's going to be a predictor of impaired glucose tolerance.
Narrator: There are a number of questions about where you
can find these slides.
I'll email them out to all the
participants on the call today.
And then the recording of this webinar, as well as the
slides, will be posted to the HealthTeamWorks website, which
is www.healthteamworks.org.
Let's see.
Next question is, in recommending exercise, what is
the normal heart rate target for pregnant women?
Dr. Linda Barbour: That's a great question.
And that's actually been looked at.
I didn't have time to go through that data.
It depends how fit you are.
There have actually been some really nice studies done
looking at exactly that question.
And in women who are unfit, which is probably a lot of our
women who are overweight or obese, the recommended target
heart rate is actually around 140.
However, women who are fit, the recommended heart rate is
actually up to 160, believe it or not.
Because they are already fit, and that does not seem to in
any way decrease placental perfusion or have any
kinodynamic sequelae.
So 140 for probably most of our women.
The women who are doing marathons and want to continue
them for awhile, 160 is reasonable.
But the most important things about exercise in pregnancy is
that women do not get overheated, because if they
get overheated, the baby gets overheated.
That they're adequately hydrated, and
they don't get ketotic.
So those are the most important things, is just to
make sure women are well-hydrated and are not
exercising in a sauna.
There are some exercise programs where they advertise
that you can lose a lot of weight by exercising in rooms
101, 102 degrees.
You're right, they become dehydrated is what happens.
So I think those are also very important considerations.
Narrator: Are there any other questions on the line?
You can unmute with *6, or you can go ahead and type them in.
I'd like to acknowledge the funding source for this
conference.
This webinar is made possible in part by the Department of
Health and Human Services Office of the Assistant
Secretary for Health, Office on Women's Health Region 8.
All right.
Doesn't look like there are any more questions.
At this point, we'd like to conclude the webinar.
This will be up on our HealthTeamWorks website, as
Emily mentioned.
And questions that anyone has in the future can be directed
to HealthTeamWorks, and we'll be happy to field those
questions as best we can.
And we'd like to thank everyone for their time and
attention this afternoon.