Shin Y. Kim

Trends in Pre-pregnancy Obesity in Nine States, 1993-2003

Objective: Pre‐pregnancy obesity poses risks to both pregnant women and their infants. This study used a large population‐based data source to examine trends, from 1993 through 2003, in the prevalence of pre‐pregnancy obesity among women who delivered live infants.

Maternal obesity and risk of cesarean delivery: a meta‐analysis

Despite numerous studies reporting an increased risk of cesarean delivery among overweight or obese compared with normal weight women, the magnitude of the association remains uncertain. Therefore, we conducted a meta‐analysis of the current literature to provide a quantitative estimate of this association. We identified studies from three sources: (i) a PubMed search of relevant articles published between January 1980 and September 2005; (ii) reference lists of publications selected from the search; and (iii) reference lists of review articles published between 2000 and 2005. We included cohort designed studies that reported obesity measures reflecting pregnancy body mass, had a normal weight comparison group, and presented data allowing a quantitative measurement of risk. We used a Bayesian random effects model to perform the meta‐analysis and meta‐regression. Thirty‐three studies were included. The unadjusted odd ratios of a cesarean delivery were 1.46 [95% confidence interval (CI): 1.34–1.60], 2.05 (95% CI: 1.86–2.27) and 2.89 (95% CI: 2.28–3.79) among overweight, obese and severely obese women, respectively, compared with normal weight pregnant women. The meta‐regression found no evidence that these estimates were affected by selected study characteristics. Our findings provide a quantitative estimate of the risk of cesarean delivery associated with high maternal body mass.

Maternal obesity and risk of neural tube defects: a metaanalysis

We conducted a metaanalysis of published evidence on the relationship between maternal obesity and the risk of neural tube defects (NTDs). Eligible studies were identified from 3 sources: (1) PubMed search of articles that were published from January 1980 through January 2007, (2) reference lists of publications that were selected from the PubMed search, and (3) reference lists of review articles on obesity and maternal outcomes that were published from January 2000 through January 2007. Twelve studies met inclusion criteria. A Bayesian random effects model was used for the metaanalysis and metaregression. Unadjusted odds ratios for an NTD-affected pregnancy were 1.22 (95% CI, 0.99-1.49), 1.70 (95% CI, 1.34-2.15), and 3.11 (95% CI, 1.75-5.46) among overweight, obese, and severely obese women, respectively, compared with normal-weight women. None of the study characteristics included in the metaregression analysis affected the results significantly. Maternal obesity is associated with an increased risk of an NTD-affected pregnancy.

Prevalence Estimates of Gestational Diabetes Mellitus in the United States, Pregnancy Risk Assessment Monitoring System (PRAMS), 2007–2010

Introduction The true prevalence of gestational diabetes mellitus (GDM) is unknown. The objective of this study was 1) to provide the most current GDM prevalence reported on the birth certificate and the Pregnancy Risk Assessment Monitoring System (PRAMS) questionnaire and 2) to compare GDM prevalence from PRAMS across 2007–2008 and 2009–2010. Methods We examined 2010 GDM prevalence reported on birth certificate or PRAMS questionnaire and concordance between the sources. We included 16 states that adopted the 2003 revised birth certificate. We also examined trends from 2007 through 2010 and included 21 states that participated in PRAMS for all 4 years. We combined GDM prevalence across 2-year intervals and conducted t tests to examine differences. Data were weighted to represent all women delivering live births in each state. Results GDM prevalence in 2010 was 4.6% as reported on the birth certificate, 8.7% as reported on the PRAMS questionnaire, and 9.2% as reported on either the birth certificate or questionnaire. The agreement between sources was 94.1% (percent positive agreement = 3.7%, percent negative agreement = 90.4%). There was no significant difference in GDM prevalence between 2007–2008 (8.1%) and 2009–2010 (8.5%, P = .15). Conclusion Our results indicate that GDM prevalence is as high as 9.2% and is more likely to be reported on the PRAMS questionnaire than the birth certificate. We found no statistical difference in GDM prevalence between the 2 phases. Further studies are needed to understand discrepancies in reporting GDM by data source.

Percentage of gestational diabetes mellitus attributable to overweight and obesity.

OBJECTIVES We calculated the percentage of gestational diabetes mellitus (GDM) attributable to overweight and obesity. METHODS We analyzed 2004 through 2006 data from 7 states using the Pregnancy Risk Assessment Monitoring System linked to revised 2003 birth certificate information. We used logistic regression to estimate the magnitude of the association between prepregnancy body mass index (BMI) and GDM and calculated the percentage of GDM attributable to overweight and obesity. RESULTS GDM prevalence rates by BMI category were as follows: underweight (13-18.4 kg/m(2)), 0.7%; normal weight (18.5-24.9 kg/m(2)), 2.3%; overweight (25-29.9 kg/m(2)), 4.8%; obese (30-34.9 kg/m(2)), 5.5%; and extremely obese (35-64.9 kg/m(2)), 11.5%. Percentages of GDM attributable to overweight, obesity, and extreme obesity were 15.4% (95% confidence interval [CI] = 8.6, 22.2), 9.7% (95% CI = 5.2, 14.3), and 21.1% (CI = 15.2, 26.9), respectively. The overall population-attributable fraction was 46.2% (95% CI = 36.1, 56.3). CONCLUSIONS If all overweight and obese women (BMI of 25 kg/m(2) or above) had a GDM risk equal to that of normal-weight women, nearly half of GDM cases could be prevented. Public health efforts to reduce prepregnancy BMI by promoting physical activity and healthy eating among women of reproductive age should be intensified.

Association of maternal body mass index, excessive weight gain, and gestational diabetes mellitus with large-for-gestational-age births.

OBJECTIVE: To estimate the percentage of large-for-gestational age (LGA) neonates associated with maternal overweight and obesity, excessive gestational weight gain, and gestational diabetes mellitus (GDM)—both individually and in combination—by race or ethnicity. METHODS: We analyzed 2004–2008 linked birth certificate and maternal hospital discharge data of live, singleton deliveries in Florida. We used multivariable logistic regression to assess the independent contributions of mothers prepregnancy body mass index (BMI), gestational weight gain, and GDM status on LGA (birth weight-for-gestational age 90th percentile or greater) risk by race and ethnicity while controlling for maternal age, nativity, and parity. We then calculated the adjusted population-attributable fraction of LGA neonates to each of these exposures. RESULTS: Large-for-gestational age prevalence was 5.7% among normal-weight women with adequate gestational weight gain and no GDM and 12.6%, 13.5% and 17.3% among women with BMIs of 25 or higher, excess gestational weight gain, and GDM, respectively. A reduction ranging between 46.8% in Asian and Pacific Islanders and 61.0% in non-Hispanic black women in LGA prevalence might result if women had none of the three exposures. For all race or ethnic groups, GDM contributed the least (2.0–8.0%), whereas excessive gestational weight gain contributed the most (33.3–37.7%) to LGA. CONCLUSION: Overweight and obesity, excessive gestational weight gain, and GDM all are associated with LGA; however, preventing excessive gestational weight gain has the greatest potential to reduce LGA risk. LEVEL OF EVIDENCE: III

Prevalence and characteristics associated with gestational weight gain adequacy.

OBJECTIVE: To estimate the prevalence of gestational weight gain adequacy according to the 2009 Institute of Medicine recommendations and examine demographic, behavioral, psychosocial, and medical characteristics associated with inadequate and excessive gain stratified by prepregnancy body mass index (BMI) category. METHODS: We used cross-sectional, population-based data on women delivering full-term (37 weeks of gestation or greater), singleton neonates in 28 states who participated in the 2010 or 2011 Pregnancy Risk Assessment Monitoring System. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for inadequate and excessive compared with adequate gain, stratified by prepregnancy BMI. RESULTS: Overall, 20.9%, 32.0%, and 47.2% of women gained inadequate, adequate, and excessive gestational weight, respectively. Prepregnancy BMI was strongly associated with weight gain outside recommendations. Compared with normal-weight women (prevalence 51.8%), underweight women (4.2%) had decreased odds of excessive gain (adjusted OR 0.50, CI 0.40–0.61), whereas overweight and obese class I, II, and III (23.6%, 11.7%, 5.4%, and 3.5%, respectively) women had increased odds of excessive gain (adjusted OR range 2.07, CI 1.63–2.62 to adjusted OR 2.99, CI 2.63–3.40). Underweight and obese class II and III women had increased odds of inadequate gain (adjusted OR 1.25, CI 1.01–1.55 to 1.86, CI 1.45–2.36). Most characteristics associated with weight gain adequacy were demographic such as racial or ethnic minority status and education and varied by prepregnancy BMI. Notably, one behavioral characteristic—smoking cessation—was associated with excessive gain among normal-weight and obese women. CONCLUSION: Most women gained weight outside recommendations. Understanding characteristics associated with inadequate or excessive weight gain may identify potentially at-risk women and inform much-needed interventions. LEVEL OF EVIDENCE: III

Fraction of Gestational Diabetes Mellitus Attributable to Overweight and Obesity by Race/Ethnicity, California, 2007–2009

OBJECTIVES We calculated the racial/ethnic-specific percentages of gestational diabetes mellitus (GDM) attributable to overweight and obesity. METHODS We analyzed 1 228 265 records of women aged 20 years or older with a live, singleton birth in California during 2007 to 2009. Using logistic regression, we estimated the magnitude of the association between prepregnancy body mass index and GDM and calculated the percentages of GDM attributable to overweight and obesity overall and by race/ethnicity. RESULTS The overall estimated GDM prevalence ranged from 5.4% among White women to 11.9% among Asian/Pacific Islander women. The adjusted percentages of GDM deliveries attributable to overweight and obesity were 17.8% among Asians/Pacific Islander, 41.2% among White, 44.2% among Hispanic, 51.2% among Black, and 57.8% among American Indian women. Select Asian subgroups, such as Vietnamese (13.0%), Asian Indian (14.0%), and Filipino (14.2%), had the highest GDM prevalence, but the lowest percentage attributable to obesity. CONCLUSIONS Elevated prepregnancy body mass index contributed to GDM in all racial/ethnic groups, which suggests that decreasing overweight and obesity among women of reproductive age could reduce GDM, associated delivery complications, and future risk of diabetes in both the mother and offspring.

Gestational diabetes and childhood obesity: what is the link?

Purpose of review To review recently published studies examining the role of prepregnancy obesity in the relationship between gestational diabetes mellitus and childhood obesity. Recent findings Seven epidemiologic studies published from January 2011 to February 2012 differentiate between preexisting diabetes mellitus and gestational diabetes mellitus, and six of them examine the role of maternal obesity. In studies that account for maternal obesity as a covariate, the association between gestational diabetes mellitus and childhood obesity is attenuated significantly after adjustment for prepregnancy BMI. In the one study that does not adjust for maternal obesity, maternal glucose level during pregnancy is associated with greater offspring adiposity, independent of the childs diet and lifestyle. Summary This review shows a positive association between maternal gestational diabetes mellitus and offspring overweight and obesity that is attenuated significantly after adjustment for prepregnancy BMI. The relationship between maternal gestational diabetes mellitus and offspring overweight and obesity could reflect fetal programming, shared genes and/or shared environments, such as postnatal diet and physical activity. Maternal gestational hyperglycemia and subsequent fetal hyperinsulinemia may predispose offspring to increased adiposity, impaired glucose tolerance, hyperinsulinemia, and insulin resistance. Because maternal obesity is a more prevalent condition than gestational diabetes mellitus and strongly associated with offspring obesity, effective interventions addressing prepregnancy obesity need to be further explored as they may have a greater public health impact on childhood overweight and obesity than those targeting women with gestational diabetes mellitus.

The Contribution of Clinic-Based Interventions to Reduce Prenatal Smoking Prevalence Among US Women

OBJECTIVES We sought to estimate the effect of universal implementation of a clinic-based, psychosocial smoking cessation intervention for pregnant women. METHODS We used data from US birth certificates (2005) and the Pregnancy Risk Assessment Monitoring System (2004) to estimate the number of women smoking at conception. To calculate the number of women eligible to receive the cessation intervention, we used estimates from the literature of the percentage of women who quit spontaneously (23%), entered prenatal care before the third trimester (96.5%), and disclosed smoking to their provider (75%). We used the pooled relative risk (RR) for continued smoking from the 2004 Cochrane Review as our measure of the interventions effectiveness (RR = 0.94). RESULTS We estimated that 944,240 women smoked at conception. Of these, 23.0% quit spontaneously, 6.3% quit with usual care, and an additional 3.3% quit because of the intervention, leaving 67.4% smoking throughout pregnancy. The calculated smoking prevalence in late pregnancy decreased from 16.4% to 15.6% because of the intervention. CONCLUSIONS Universal implementation of a best-practice, clinic-based intervention would increase the total number of quitters but would not substantially reduce smoking prevalence among pregnant women.