Association of Prenatal Physical Activity and Gestational Weight Gain: Results from the First Baby Study

Abstract

Background

In response to increasing rates of excessive gestational weight gain (GWG) and evidence of postpartum weight retention and long-term overweight and obesity, the Institute of Medicine (IOM) revised their guidelines for GWG in 2009. Prenatal physical activity is recommended, although its role in preventing excessive GWG is unclear. We sought to understand the association between prenatal physical activity and GWG in a longitudinal cohort.

Methods

During a baseline survey at 34 weeks, women (n = 3,006) reported their height, prepregnancy weight, and physical activity during pregnancy. GWG was self-reported at 1-month postpartum. Multivariable logistic regression adjusting for age, race/ethnicity, education, poverty status, marital status, gestational age at the time of delivery, and smoking was used to model the association between adequate physical activity during pregnancy and exceeding the IOM recommendations for GWG.

Findings

Overweight women were most likely to exceed the IOM recommendations for GWG (78.7%), followed by obese women and normal weight women (65.0% and 42.4%, respectively). The majority of women participated in some physical activity during pregnancy, with 41.2% engaging in 60 to 149 minutes and 32.1% engaging in at least 150 minutes of physical activity per week. In adjusted analysis, meeting the physical activity guidelines was associated with a 29% (confidence interval, 0.57–0.88) lower odds of exceeding the IOM recommendations for GWG compared with inactive women.

Conclusions

Findings of high rates of excessive GWG, especially among women with overweight and obesity, are concerning given the associated health burdens. The association of guideline-concordant physical activity with appropriate GWG suggests this is an important target for future interventions.

Introduction

The widespread adverse health and economic effects of the obesity epidemic are well described (Flegal, Carroll, Ogden, & Curtin, 2010). The majority of women of childbearing age are already overweight or obese, which elevates the risk of gestational diabetes, preeclampsia, eclampsia, cesarean delivery, and macrosomic infants (Baeten, Bukusi, & Lambe, 2001; Institute of Medicine [IOM] & National Research Council [NRC], 2009). Also, nearly half of normal weight women and two thirds of overweight and obese women are exceeding the IOM guidelines for appropriate gestational weight gain (GWG) during pregnancy (Chu, Callaghan, Bish, & D'Angelo, 2009; IOM & NRC, 2009; Martin et al., 2007). Excessive GWG is an important contributor to postpartum weight retention and long-term overweight and obesity; one quarter of women with a normal prepregnancy body mass index (BMI) who gain more than 20 kg during pregnancy will move up one BMI category (i.e., from normal weight to overweight) at 6 months postpartum (Nohr et al., 2008; Viswanathan et al., 2008). Even more important, high GWG is independently associated with poor pregnancy outcomes, including premature birth, large-for-gestational age infants, lower breastfeeding initiation rates, and increased risk of cesarean delivery (Viswanathan et al., 2008).

In response to increasing rates of excessive GWG and evidence of associated negative outcomes (Viswanathan et al., 2008), the IOM revised their guidelines for GWG in 2009 (IOM & NRC, 2009). The updated guidelines for GWG are based on prepregnancy BMI, with lower GWG recommended for overweight and obese women compared with normal weight women. Although normal weight (BMI = 18.5–24.9 kg/m²) women are recommended to gain 11.5 to 16 kg, women who are overweight (BMI = 25.0–29.9 kg/m²) are expected to limit weight gain to 7 to 11.5 kg (IOM & NRC, 2009). Obese women (BMI ≥ 30.0 kg/m²) are further restricted, with recommendations to gain only 5 to 9 kg during pregnancy (IOM & NRC, 2009). Although GWG limited to these recommended ranges has been associated with reduced maternal and infant morbidity, little is known about how modifiable prenatal behaviors influence GWG.

Describing characteristics and behaviors associated with excessive GWG may offer important clinical insights on how to limit the increasing problem of excessive weight gain during pregnancy. Identifying modifiable factors influencing GWG may provide useful targets for intervention and prevention. For example, physical activity during pregnancy is recommended by both the American College of Obstetricians and Gynecologists and United States Federal Guidelines, but whether prenatal physical activity has an important role in preventing excessive GWG is unclear (American College of Obstetricians and Gynecologists, 2002; Physical Activity Guidelines Advisory Committee, 2008). In fact, the 2009 IOM report specifically recommended that studies be conducted on the effect of physical activity on weight gain during pregnancy (IOM & NRC, 2009). Subsequent studies have suggested that physical activity, both preconception and prenatal, is inversely associated with excessive GWG (Stuebe, Oken, & Gillman, 2009; Weisman, Hillemeier, Downs, Chuang, & Dyer, 2010). We hypothesize that adequate physical activity during pregnancy helps women to avoid excessive GWG. This benefit may be even greater for women with overweight and obesity, given tighter restrictions on appropriate weight gain. Using a unique longitudinal cohort of women having their first child, the aim of this study was to understand the association between prenatal physical activity and GWG, using data collected at the baseline and 1-month postpartum time points.