Obesity in pregnancy

If you are obese, your BMI is 30.0 + before pregnancy. About 1 in 4 women of reproductive age in the
United States is obese. 1
DETERMINATION of OBESITY
The World Health Organization (WHO) and the National Institutes of Health (NIH) define weight by body
mass index (BMI) as follows 2,3 :
BMI Weight Classification
18.5-24.9 Normal
25.0-29.9 Overweight
Obese
30.0-34.9 Class I
35.0-39.9 Class II
>=40.0 Class III
Online BMI Calculator 3
The 1999-2002 National Health and Nutrition Survey (NHANES) found that approximately one third of adult
women are obese, with this being greatest among non-Hispanic black women (49%) compared with Mexican-
American women (38%) and non-Hispanic white women (31%.) 4
RECOMMENDATIONS FOR WEIGHT GAIN IN PREGNANCY 5
Height and weight should be recorded at the initial prenatal visit to determine BMI.
Prenatal weight gain recommendations are based off of the Institute of Medicine (IOM) guidelines as follows:
Normal weight women: 25-35 lbs
Overweight women: 15-25 lbs
Obese women: 15 lb
See the newest chart from the National Institute of Medicine for more detail: Table 1, pg 2.
TRACKING YOUR WEIGHT GAIN
Pregnant women can chart their weight gain alongside the average pattern curve, as in the example provided by
March of Dimes.
BE CONSISTENT: Weight should be taken at the same time of day, in the same way (clothed or not).
Weight Gain Chart Example 6
COMPLICATIONS DURING PREGNANCY- The Mother
Women who are overweight when they get pregnant and during their pregnancy are at higher risk for many
complications. They include the following:
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Infertility: Some overweight women are unable to get pregnant.
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Miscarriage: The baby may die in the womb prior to 20 weeks of pregnancy.
Stillbirth: The baby may die in the womb after 20 weeks of pregnancy but before birth.
Preeclampsia and High Blood Pressure: Only pregnant women are able to get preeclampsia, and the risk
is increased with being overweight. It can increase the chances of a preterm birth (birth prior to 37 weeks
of completed pregnancy.)
Gestational Diabetes: Diabetes during pregnancy
Labor and Birth Complications:
Large for gestational age baby
Increased risk for cesarean section
Complications with anesthesia
Increased risk for post-surgical wound infection
Higher rates of surgical blood loss
Intrapartum complications, such as difficulty estimating fetal weight, inability
to obtain external fetal heart rate and uterine contraction patterns, and trouble
performing emergent cesarean delivery.
Studies have shown that Class I and II obesity are associated with a higher risk of gestational diabetes,
gestational hypertension, preeclampsia, and fetal macrosomia in comparison with a BMI of less than
30 7,8,9,10,11 . Additionally, the cesarean delivery rate was seem to increase with BMI. 7
Operative and postoperative complications have been shown to include higher rates of excessive blood loss,
increased operative time, wound infection, and endometriosis. 12, 13, 14 Additionally, surgery in obese women
can lead to anesthetic challenges, with difficulty in placing epidural, need for multiple attempts, and respiratory
events from intubation problems. 15
POST PREGNANCY COMPLICATIONS
Incremental increases in gestational weight gain beyond that recommended for obese women substantially
increase the risk of weight retention at 1 year postpartum. 16
COMPLICATIONS FOR THE BABY
A majority of babies born to overweight or obese mothers are born healthy, however, there is an increased risk
for many complications if a woman is overweight or obese during pregnancy. These include:
Birth defects, particularly neural tube defects
Preterm birth
Injury, such as shoulder dystocia during birth, due to large size of the baby.
Death after birth
Large size (macrosomia)
Obesity during childhood
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Some studies have reported a greater rate of premature delivery for obese women than those who are of a
normal weight, 8,17 but some have reported that pre-pregnancy obesity is associated with a lower rate of
spontaneous preterm birth, 18 thus this issue is still unclear.
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As far as neural tube defects, it has been shown that the number among obese mothers is double that of normal
weight mothers (after correcting for diabetes as a potential confounding variable.) 19,20,21
Many studies have shown that maternal obesity and excessive weight gain in pregnancy are in fact associated
with macrosomia, 9, 22,23,24 and that these babies are in turn at increased risk for childhood obesity. 10, 25
HEALTH CARE COST BURDEN
Obesity in pregnancy has been shown by the CDC to be associated with an increase in the use of health care
services. These can include:
Greater use of inpatient and outpatient health care services
Increased length of hospital stays for delivery
Greater use of physician services
Less use of services by nurse practitioners and physician assistants during prenatal visits
Increased prenatal care costs
The main study referenced was adjusted for age, race/ethnic group, level of education, and parity. In this study,
it was found that:
The mean length of hospital stay was significantly longer for women who were overweight, obese, very
obese, and extremely obese in comparison with women with a normal BMI, particularly due to increased
rates of cesarean delivery and obesity-related high-risk conditions.
A higher than normal BMI was associated with significantly more prenatal fetal tests, obstetrical
ultrasonographic examinations, medications from outpatient pharmacies, calls to the department of
obstetrics and gynecology, and prenatal visits with physicians.
Fewer of these visits were with nurse practitioners and physician assistants. 26
The costs are not only limited to the mother and her delivery. Babies born to obese mothers often need
admission to neonatal intensive care units more often than those born to normal weight mothers. 27
Unfortunately, very few studies have been done looking at the economic impact of maternal obesity. There are
no good studies to show robust estimates of actual cost. 38 Even without these specific numbers, it seems clear
that the impact is significant, and hopefully in the near future, more work will be done to support this.
RISK REDUCTION PRE-PREGNANCY (Primary Prevention)
Before conceiving:
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Get a preconception check-up
Discuss healthy eating and exercise with your health care provider (to help lose weight before
pregnancy)
Create a healthy eating plan, with the help of the U.S.D.A. Choose My Plate online tool
Consider weight reduction surgery
WEIGHT LOSS SURGERY PRE-PREGNANCY
Weight loss surgery before pregnancy can decrease the chances of experiencing weight-related pregnancy
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complications, if it successfully leads to a sustained reduction in weight. Many providers therefore will
recommend waiting at least 1 year after the surgery before trying to get pregnant. While uncommon, women
who have undergone weight reduction surgery may have different complications during pregnancy, which
should be discussed with the health care provider prior to trying to conceive.
Early studies on pregnancy after bariatric (weight loss) surgery showed complications such as gastrointestinal
bleeding28 , anemia29 , intrauterine growth restriction30 , and neural tube defects, 31, 32 however more recent
studies suggest that previous bariatric surgery is not associated with adverse perinatal outcomes. 33, 34
Research has shown that pregnancies after bariatric surgery are in fact associated with fewer complications
such as gestational diabetes, hypertension, macrosomia, and cesarean delivery than in obese women who had
not had the surgery. 34, 35,36
Suggestions for women thinking of conceiving, who have undergone bariatric surgery:
Those with gastric banding are at risk of becoming pregnant unexpectedly after weight loss following the
surgery35 Patients should be advised to delay pregnancy 12-18 months after surgery
Women with a gastric band should be monitored by their surgeon in case adjustment of the band may
become necessary
Patients should be monitored for nutritional deficiencies, and vitamin supplementation should be done as
necessary
RISK REDUCTION DURING PREGNANCY (Secondary Prevention)
During pregnancy:
Get early, regular prenatal care
Determine the appropriate level of weight gain by BMI, and physicians should discuss this with the
patient
Exercise most days (as directed by the health care provider). Safe exercises include walking, swimming,
riding a stationary bike, taking pregnancy aerobics, or yoga classes.
Dietary modifications can help reduce maternal weight gain and improve obstetric outcome in
overweight pregnant women37 Preconception counseling ans assessment are highly recommended due to the increased risk of several
pregnancy complications in overweight or obese women 1
Screening for gestational diabetes should be considered during the first trimester, and later in pregnancy
if the initial screen is negative22 ACOG RECOMMENDATIONS
Recommendations for obese women who are pregnant or planning a pregnancy include:
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Preconception counseling
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Provision of specific information concerning the maternal and fetal risks of obesity in pregnancy
Consideration of screening for gestational diabetes upon presentation of in the first trimester, and
repeated screening later in pregnancy if results are initially negative.

Assessment and possible supplementation of vitamin B12, folate, iron, and calcium for women who have
undergone bariatric surgery
Possible use of graduated compression stockings, hydration, and early mobilization during and after
cesarean delivery
Anesthesiology consult (prior to delivery date if possible)
Continuation of nutrition counseling and exercise program after delivery, and consultation with weight
loss specialists before attempting another pregnancy.
KEY FINDINGS AND RECOMMENDATIONS
Suggested weight gain during pregnancy varies based on BMI prior to conception
Obesity in pregnancy is correlated with a number of possible complications for both the mother and
child, and these complications tend to increase with the severity of obesity in the mother.
Diet modification is very important, before, during, and after pregnancy, to ensure the best obstetric
outcome
Regular exercise is very important to lowering the risk of many obesity related pregnancy complications
Bariatric surgery does not exclude women from being able to become pregnant, and if enough time is
allowed, can dramatically decrease the risk for obesity related pregnancy complications
Obesity in pregnancy can lead to extensive use of health care resources, and primary prevention through
preconception weight loss could significantly reduce the resource use and health care cost.
Complication possibilities should be discussed with potential obese mothers as early as possible, prior to
conception ideally.
For the most up-to-date recommendations, please see the 2009 report from the National Institute of
Medicine.
REFERENCES
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* Image courtesy of http://www.bebemagico.com/wp-content/uploads/2010/06/obesity-and-pregnancy.jpg
1. ACOG Committee Opinion Number 315, September 2005 (Reaffirmed 2008.)
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