Patricia M. Dietz

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.

Infant Morbidity and Mortality Attributable to Prenatal Smoking in the U.S.

BACKGROUND Although prenatal smoking continues to decline, it remains one of the most prevalent preventable causes of infant morbidity and mortality in the U.S. PURPOSE The aim of this study was to estimate the proportion of preterm deliveries, term low birth weight deliveries, and infant deaths attributable to prenatal smoking. METHODS Associations were estimated for prenatal smoking and preterm deliveries, term low birth weight (<2500 g) deliveries, sudden infant death syndrome (SIDS), and preterm-related deaths among 3,352,756 singleton, live births using the U.S. Linked Birth/Infant Death Data Set, 2002 birth cohort. The 2002 data set is the most recent, in which 49 states used the same standardized smoking-related question on the birth certificate. Logistic regression models estimated ORs of prenatal smoking for each outcome, and the prenatal smoking population attributable fraction was calculated for each outcome. RESULTS Prenatal smoking (11.5% of all births) was significantly associated with very (AOR=1.5, 95% CI=1.4, 1.6); moderate (AOR=1.4, 95% CI=1.4, 1.4); and late (AOR=1.2, 95% CI=1.2, 1.3) preterm deliveries; term low birth weight deliveries (AOR=2.3, 95% CI=2.3, 2.5); SIDS (AOR=2.7, 95% CI=2.4, 3.0); and preterm-related deaths (AOR=1.5, 95% CI=1.4, 1.6). It was estimated that 5.3%-7.7% of preterm deliveries, 13.1%-19.0% of term low birth weight deliveries, 23.2%-33.6% of SIDS, and 5.0%-7.3% of preterm-related deaths were attributable to prenatal smoking. Assuming prenatal smoking rates continued to decline after 2002, these PAFs would be slightly lower for 2009 (4.4%-6.3% for preterm-related deaths, 20.2%-29.3% for SIDS deaths). CONCLUSIONS Despite recent declines in the prenatal smoking prevalence, prenatal smoking continues to cause a substantial number of infant deaths in the U.S.

Association between Obesity during Pregnancy and Increased Use of Health Care

BACKGROUND In the United States, obesity during pregnancy is common and increases obstetrical risks. An estimate of the increase in use of health care services associated with obesity during pregnancy is needed. METHODS We used electronic data systems of a large U.S. group-practice health maintenance organization to identify 13,442 pregnancies among women 18 years of age or older at the time of conception that resulted in live births or stillbirths. The study period was between January 1, 2000, and December 31, 2004. We assessed associations between measures of use of health care services and body-mass index (BMI, defined as the weight in kilograms divided by the square of the height in meters) before pregnancy or in early pregnancy. The women were categorized as underweight (BMI <18.5), normal (BMI 18.5 to 24.9), overweight (BMI 25.0 to 29.9), obese (BMI 30.0 to 34.9), very obese (BMI 35.0 to 39.9), or extremely obese (BMI > or =40.0). The primary outcome was the mean length of hospital stay for delivery. RESULTS After adjustment for age, race or ethnic group, level of education, and parity, the mean (+/-SE) length of hospital stay for delivery was significantly (P<0.05) greater among women who were overweight (3.7+/-0.1 days), obese (4.0+/-0.1 days), very obese (4.1+/-0.1 days), and extremely obese (4.4+/-0.1 days) than among women with normal BMI (3.6+/-0.1 days). A higher-than-normal BMI was associated with significantly more prenatal fetal tests, obstetrical ultrasonographic examinations, medications dispensed from the outpatient pharmacy, telephone calls to the department of obstetrics and gynecology, and prenatal visits with physicians. A higher-than-normal BMI was also associated with significantly fewer prenatal visits with nurse practitioners and physician assistants. Most of the increase in length of stay associated with higher BMI was related to increased rates of cesarean delivery and obesity-related high-risk conditions. CONCLUSIONS Obesity during pregnancy is associated with increased use of health care services.

Estimates of Nondisclosure of Cigarette Smoking Among Pregnant and Nonpregnant Women of Reproductive Age in the United States

Although clinic-based studies have used biochemical validation to estimate the percentage of pregnant women who deny smoking but are actually smokers, a population-based estimate of nondisclosure of smoking status in US pregnant women has not been calculated. The authors analyzed data from the 1999-2006 National Health and Nutrition Examination Survey and estimated the percentage of 994 pregnant and 3,203 nonpregnant women 20-44 years of age who did not report smoking but had serum cotinine levels that exceeded the defined cut point for active smoking (nondisclosure). Active smoking was defined as self-reporting smoking or having a serum cotinine concentration that exceeded the cut point for active smoking. Overall, 13.0% (95% confidence interval (CI): 8.8, 17.1) of pregnant women and 29.7% (95% CI: 27.3, 32.1) of nonpregnant women were active smokers. Nondisclosure was higher among pregnant active smokers (22.9%, 95% CI: 11.8, 34.6) than among nonpregnant smokers (9.2%, 95% CI: 7.1, 11.2). Among pregnant active smokers, nondisclosure was associated with younger age (20-24 years). Among nonpregnant active smokers, nondisclosure was associated with Mexican-American and non-Hispanic black race/ethnicity. Studies and surveillance systems that rely on self-reported smoking status are subject to underestimation of smoking prevalence, especially among pregnant women, and underreporting may vary by demographic characteristics.

Combined effects of prepregnancy body mass index and weight gain during pregnancy on the risk of preterm delivery

Background: The association between excessive gestational weight gain and preterm delivery is unclear, as is the association between low gestational weight gain and preterm delivery among overweight and obese women. Methods: Using data from the Pregnancy Risk Assessment Monitoring System in 21 states, we estimated the risk of very (20–31 weeks) and moderately (32–36 weeks) preterm delivery associated with a combination of prepregnancy body mass index (BMI) and gestational weight gain among 113,019 women who delivered a singleton infant during 1996–2001. We categorized average weight gain (kilograms per week) as very low (<0.12), low (0.12–0.22), moderate (0.23–0.68), high (0.69–0.79), or very high (>0.79). We categorized prepregnancy BMI (kg/m2) as underweight (<19.8), normal (19.8–26.0), overweight (26.1–28.9), obese (29.0–34.9), or very obese (≥35.0). We examined associations for all women and for all women with no complications adjusting for covariates. Results: There was a strong association between very low weight gain and very preterm delivery that varied by prepregnancy BMI, with the strongest association among underweight women (adjusted odds ratio = 9.8; 95% confidence interval = 7.0–13.8) and the weakest among very obese women (2.3; 1.8–3.1). Very low weight gain was not associated with moderately preterm delivery for overweight or obese women. Women with very high weight gain had approximately twice the odds of very preterm delivery, regardless of prepregnancy BMI. Conclusions: This study supports concerns about very low weight gain during pregnancy, even among overweight and obese women, and also suggests that high weight gain, regardless of prepregnancy BMI, deserves further investigation.

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.

Depression and Treatment Among U.S. Pregnant and Nonpregnant Women of Reproductive Age, 2005–2009

BACKGROUND Depression is often undiagnosed and untreated. It is not clear if differences exist in the diagnosis and treatment of depression among pregnant and nonpregnant women. We sought to estimate the prevalence of undiagnosed depression, treatment by modality, and treatment barriers by pregnancy status among U.S. reproductive-aged women. METHODS We identified 375 pregnant and 8,657 nonpregnant women 18-44 years of age who met criteria for past-year major depressive episode (MDE) from 2005-2009 nationally representative data. Chi-square statistics and adjusted prevalence ratios (aPR) were calculated. RESULTS MDE in pregnant women (65.9%) went undiagnosed more often than in nonpregnant women (58.6%) (aPR 1.1, 95% confidence interval [CI] 1.0-1.3). Half of depressed pregnant (49.6%) and nonpregnant (53.7%) women received treatment (aPR 1.0, 95% CI 0.90-1.1), with prescription medication the most common form for both pregnant (39.6%) and nonpregnant (47.4%) women. Treatment barriers did not differ by pregnancy status and were cost (54.8%), opposition to treatment (41.7%), and stigma (26.3%). CONCLUSIONS Pregnant women with MDE were no more likely than nonpregnant women to be diagnosed with or treated for their depression.

Weight-Management Interventions for Pregnant or Postpartum Women

BACKGROUND A review of randomized controlled trials of weight-management interventions for pregnant or postpartum women was conducted to assess whether effective weight-management interventions exist for this population. METHODS The MEDLINE, EMBASE, PsycINFO, Sociological Abstracts, and CINAHL databases were searched, as well as the reference lists of relevant publications. English-language articles published between January 1985 and August 2007 that used a randomized controlled trial study design and incorporated a weight-related outcome measure were reviewed. All potentially relevant articles were reviewed separately, and final selections were based on consensus reached through discussion. RESULTS Three studies met the inclusion criteria, one conducted among pregnant women and two among postpartum women. The interventions addressed modifications in diet and exercise and included individual or group-counseling sessions combined with written and telephone correspondence or food and exercise diaries. In two studies, the weight-related outcome was significantly better in the intervention group than in the control group. The third study found a significant interaction between weight category and intervention group. In all studies, the refusal or attrition rates were high. CONCLUSIONS While these studies indicate that interventions can help pregnant and postpartum women manage their weight, many questions remain unanswered. Several research gaps for weight-management interventions in this important population have been identified.

High pregnancy weight gain and risk of excessive fetal growth

OBJECTIVE The purpose of this study was too assess whether prepregnancy body mass index (BMI) modifies the relationship between pregnancy weight gain and large for gestational age (LGA; > 90% of birthweight for gestational age) or macrosomia (>or= 4500 g). STUDY DESIGN This was a population-based cohort study of 104,980 singleton, term births from 2000-2005. RESULTS Prepregnancy BMI modified the relationship between weight gain and LGA. Lean women had higher odds of LGA than overweight or obese women for weight gain >or= 36 lb. For macrosomia, prepregnancy BMI did not modify the association. Compared with women who gained 15-25 lb, the aOR for a gain of 26-35 lb was 1.5 (95% confidence interval [CI], 1.2-1.9), for a gain of 36-45 lb was 2.1 (95% CI, 1.7-2.7), and for a gain of >or= 46 lb was 3.9 (95% CI, 3.0-5.0). CONCLUSION Current pregnancy weight gain recommendations include weight gain ranges that are associated with increased risk of LGA and macrosomia.