Maternal Data Committee - Obesity/BMI Resources Resources

Objective: The objective of this study was to estimate the effects of low and high gestational weight gain, in different maternal Body Mass Index (BMI) classes, on obstetric and neonatal outcomes. Method: A prospective population-based cohort study of 245,526 singleton termpregnancies.Women were grouped in five categories of BMI and in three gestational weight gain categories; b8 kg (low weight gain), 8—16 kg and N16 kg (high weight gain). Obstetric and neonatal outcomes were evaluated after adjustments for maternal age, parity, smoking, year of birth. Result: Obese women with low gestational weight gain had a decreased risk for the following outcomes (adjusted odds ratio; 95% confidence interval): preeclampsia (0.52; 0.42—0.62), cesarean section (0.81; 0.73—0.90), instrumental delivery (0.75; 0.63—0.88), and LGA births (0.66; 0.59—0.75). There was a 2-fold increased risk for preeclampsia and LGA infants among average and overweight women with excessive weight gain. High gestational weight gain increased the risk for cesarean delivery in all maternal BMI classes. Conclusion: The effects of high or low gestational weight gain differ depending on maternal BMI and the outcome variable studied. Obese women may benefit from a low weight gain during pregnancy.

OBJECTIVE: To establish optimal gestational weight gain for each maternal body mass index (BMI) category based on significant risk estimates of adverse maternal and fetal outcome. METHODS: The study population consisted of 298,648 singleton pregnancies delivered in Sweden between January 1, 1994, and December 31, 2004. The number of individuals in each weight gain class was compared with the number of individuals in all other weight gain classes in the same BMI group with regard to adverse maternal and fetal outcome. Odds ratios were calculated after suitable adjustments. RESULTS: The optimal gestational weight gain in women by prepregnancy BMI was 9–22 lb (4–10 kg) for BMI less than 20; 5–22 lb (2–10 kg) for BMI 20–24.9; less than 20 lb (less than 9 kg) for BMI 25–29.9; and less than 13 lb (less than 6 kg) for BMI of 30 or more. CONCLUSION: The gestational weight gain limits for BMI categories determined in this large populationbased cohort study from Swedish Medical Registers showed that a decreased risk of adverse obstetric and neonatal outcomes was associated with lower gestational weight gain limits than was earlier recommended, especially among obese women.

OBJECTIVE: Numerous studies in the U.S. and elsewhere have reported an increased risk of gestational diabetes mellitus (GDM) among women who are overweight or obese compared with lean or normal-weight women. Despite the number and overall consistency of studies reporting a higher risk of GDM with increasing weight or BMI, the magnitude of the association remains uncertain. This meta-analysis was conducted to better estimate this risk and to explore differences across studies. RESEARCH DESIGN AND METHODS: We identified studies from three sources: 1) a PubMed search of relevant articles published between January 1980 and January 2006, 2) reference lists of publications selected from the PubMed search, and 3) reference lists of review articles on obesity and maternal outcomes published between January 2000 and January 2006. We used a Bayesian model to perform the meta-analysis and meta-regression. We included cohort-designed studies that reported obesity measures reflecting pregnancy body mass, that had a normal-weight comparison group, and that presented data allowing a quantitative measurement of risk. RESULTS: Twenty studies were included in the meta-analysis. The unadjusted ORs of developing GDM were 2.14 (95% CI 1.82–2.53), 3.56 (3.05– 4.21), and 8.56 (5.07–16.04) among overweight, obese, and severely obese compared with normal-weight pregnant women, respectively. The meta-regression analysis found no evidence that these estimates were affected by selected study characteristics (publication date, study location, parity, type of data collection [retrospective vs. prospective], and prevalence of GDM among normal-weight women). CONCLUSIONS: Our findings indicate that high maternal weight is associated with a substantially higher risk of GDM.

OBJECTIVE: The purpose of this study was to evaluate the effect of pregravid obesity and gestational diabetes mellitus (GDM) on the longitudinal accretion and distribution of adipose tissue in pregnancy. STUDY DESIGN: Women with normal glucose tolerance and GDM were evaluated before conception, early (12-14 weeks) and late (33-36 weeks) in gestation. Fat mass, lean body mass, and percent body fat were assessed longitudinally with hydrodensitometry. Serial biceps, triceps, subscapular, iliac, costal, mid thigh, and lower thigh skinfold measurements quantified the changes in fat mass distribution. Pregravid obesity was defined as >25% body fat. RESULTS: Subjects included 19 patients with GDM (5 lean women, 14 obese women), and 33 patients with normal glucose tolerance (controls; 12 lean women, 21 obese women). GDM and control subjects were similar in pregravid percent body fat (29.6% vs 27.9%, P = .47) and fat mass (20.8 kg vs 18.2 kg, P = .37). Values for subjects with GDM and controls were also similar in terms of percent body fat, fat mass, and weight gained (change in percent body fat,
0.7% vs 1.9% [P = .07]; change in fat mass, 3.8 kg vs 5.0 kg [P = .08]; change in weight, 12.0 kg vs 13.2 kg [P = .35]). Lean subjects gained more percent body fat compared with obese subjects (change in percent body fat, 3.3% vs 0.1% [P = .004]) but gained similar amounts of fat mass (change in fat mass, 4.7 kg vs 4.2 kg [P = .58]), lean body mass (7.6 kg vs 8.8 kg [P = .18]), and weight (change in weight, 12.3kg vs 13.0 kg [P = .61]) The distribution of adipose tissue that was accumulated as estimated with skinfold measurements was similar between patients with GDM and glucose tolerance (P > .05 for all changes in skinfolds), but significantly different between lean and obese patients (P< .05 for all changes in skinfolds). Lean women gained a predominance of adipose tissue peripherally over that in obese women. CONCLUSION: Lean women accrue significantly more fat mass than obese women, regardless of glucose tolerance. Pregestational obesity rather than GDM influences the distribution of adipose accretion.

Objective: The purpose of this retrospective cohort study was to review pregnancy outcomes in morbidly obese women who delivered a baby weighing 500 g or more in a large tertiary referral university hospital in Europe. Methods: Morbid obesity was defined as a BMI ≥ 40.0 kg/m2 (WHO). Only women whose BMI was calculated at their first antenatal visit were included. The obstetric outcomes were obtained from the hospital’s computerised database. Results: The incidence of morbid obesity was 0.6% in 5,824 women. Morbidly obese women were older and were more likely to be multigravidas than women with a normal BMI. The pregnancy was complicated by hypertension in 35.8% and diabetes mellitus in 20.0% of women. Obstetric interventions were high, with an induction rate of 42.1% and a caesarean section rate of 45.3%. Conclusions: Our findings show that maternal morbid obesity is associated with an alarmingly high incidence of medical complications and an increased level of obstetric interventions. Consideration should be given to developing specialised antenatal services for morbidly obese women. The results also highlight the need to evaluate the effectiveness of pre-pregnancy interventions in morbidly obese women.

OBJECTIVE: To examine the effect of gestational weight change on pregnancy outcomes in obese women. METHODS: A population-based cohort study of 120,251 pregnant, obese women delivering full-term, liveborn, singleton infants was examined to assess the risk of four pregnancy outcomes (preeclampsia, cesarean delivery, small for gestational age births, and large for gestational age births) by obesity class and total gestational weight gain. RESULTS: Gestational weight gain incidence for overweight or obese pregnant women, less than the currently recommended 15 lb, was associated with a significantly lower risk of preeclampsia, cesarean delivery, and large for gestational age birth and higher risk of small for gestational age birth. These results were similar for each National Institutes of Health obesity class (30 –34.9, 35–35.9, and 40.0 kg/m2), but at different amounts of gestational weight gain. CONCLUSION: Limited or no weight gain in obese pregnant women has favorable pregnancy outcomes

Our objective was to study the effects of maternal body mass index (BMI) on the mode of delivery for primigravid and multigravid women. A retrospective cohort study was conducted at the University College Hospital Galway, Ireland, of 5162 women delivered from 2001 to 2003. BMI at the first antenatal appointment was calculated. Comparisons were made between each of the five BMI categories separately for primigravid and multigravid women in relation to gestation at delivery, age, mode of delivery, and birthweight. There were 5162 deliveries during the time period of the study; 2006 were primigravid and 3156 were multigravid women. Overall, 2.6% of women were underweight, 49.2% were normal weight, 22.8% were overweight, 19.8% were obese, and 5.6% were morbidly obese. In comparison with women of normal weight, for overweight and obese women, there was a progressive reduction in vaginal delivery rate with increasing BMI. For morbidly obese primigravida, this reduction was by 33.5% (from 83.1% to 55.3%, x2¼39.84, p<0.001), and for multigravida was by 23.6% (from 86% to 65.7%, x2¼53.05, p<0.001). Obesity conferred a two- to threefold increased risk of delivery by emergency caesarean section for both primigravid (obese, relative risk [RR] 2.16, 95% confidence interval [CI] 1.72 to 2.73; morbidly obese, RR 2.30, CI 1.61 to 3.37) and multigravid women (obese, RR 1.97, CI 1.45 to 2.67; morbidly obese, RR 2.44, CI 1.61 to 3.69). We concluded that increasing maternal BMI exerts a progressive adverse effect on vaginal delivery rates for both primigravid and multigravid women. Obese primigravida should be counseled antenatally about the 30% risk of emergency caesarean section.

Abstract We investigated the association between 2009 IOM recommendations and adverse infant outcomes by maternal prepregnancy body mass index (BMI). Birth outcomes for 570,672 women aged 18–40 years with a singleton full-term live-birth were assessed using 2004–2007 Florida live-birth certificates. Outcomes included large-for-gestational-age (LGA) and small-for-gestationalage (SGA). Associations between gestational weight change and outcomes were assessed for 10 BMI groups by calculating proportions, and logistic regression modeling was used to produce adjusted odds ratios (aORs) to account for the effect of confounders. We created comparison categories below and above recommendations using 2009 IOM recommendations as a reference. Of importance, 41.6% of women began pregnancy as overweight and obese and 51.2% gained weight excessively during pregnancy on the basis of 2009 IOM recommendations. Proportions of LGA were higher among obese women and increased with higher weight gain. Compared with recommended weight gain, aORs for LGA were lower with less than recommended gain (aOR range: 0.27–0.77) and higher with more than recommended gain (aOR range: 1.27–5.99). However, SGA was less prevalent among obese women, and the proportion of SGA by BMI was similar with higher weight gain. Gain less than recommended was associated with increased odds of SGA (aOR range: 1.11–2.97), and gain greater than recommended was associated with decreased odds of SGA (aOR range: 0.38–0.83). Gestational weight gain influenced the risk for LGA and SGA in opposite directions. Minimal weight gain or weight loss lowered risk for LGA among obese women. Compared with 1990 IOM recommendations, 2009 recommendations include weight gain ranges that are associated with lower risk of LGA and higher risk of SGA. Awareness of these tradeoffs may assist with clinical implementation of the 2009 IOM gestational weight gain recommendations. However, our results did not consider other maternal and infant outcomes related to gestational weight gain; therefore, the findings should be interpreted with caution.

Objective. Several studies have shown an increased risk for neural tube defects associated with prepregnancy maternal obesity. Because few recent studies have examined the relation between maternal prepregnancy obesity and overweight and other birth defects, we explored the relation for several birth defects and compared our findings with those of previous studies. Methods. We conducted a population-based case-control study of several selected major birth defects using data from the Atlanta Birth Defects Risk Factor Surveillance Study. Mothers who delivered an infant with and without selected birth defects in a 5-county metropolitan Atlanta area between January 1993 and August 1997 were interviewed. Maternal body mass index (BMI) was calculated from self-reported maternal prepregnancy weight and height. Women with known preexisting diabetes were excluded. The risks for obese women (BMI >30) and overweight women (BMI 25.0 –29.9) were compared with those for average-weight women (BMI 18.5– 24.9). Results. Obese women were more likely than average-weight women to have an infant with spina bifida (unadjusted odds ratio [OR]: 3.5; 95% confidence interval [CI]: 1.2–10.3), omphalocele (
OR: 3.3; 95%
CI: 1.0 –10.3), heart defects (
OR: 2.0; 95%
CI: 1.2–3.4), and multiple anomalies (
OR: 2.0; 95%
CI: 1.0 –3.8). Overweight women were more likely than average-weight women to have infants with heart defects (
OR: 2.0; 95%
CI: 1.2–3.1) and multiple anomalies (
OR: 1.9; 95%
CI: 1.1–3.4). Conclusions. Our study confirmed the previously established association between spina bifida and prepregnancy maternal obesity and found an association for omphalocele, heart defects, and multiple anomalies among infants of obese women. We also found an association between heart defects and multiple anomalies and being overweight before pregnancy. A higher risk for some birth defects is yet another adverse pregnancy outcome associated with maternal obesity. Obesity prevention efforts are needed to increase the number of women who are of healthy weight before pregnancy. Pediatrics 2003;111:1152–1158; obesity, body mass index, pregnancy, neural tube defect, congenital anomaly, birth defect.