Sylvia E. Badon

Maternal Leisure Time Physical Activity and Infant Birth Size

Background: Associations of maternal leisure time physical activity with birth size are inconsistent. Roles of infant sex and maternal prepregnancy body mass index (BMI) in these associations have not been studied. Methods: Participants (N = 3,310) in the Omega study, a cohort in Washington State (1996–2008), reported leisure time physical activity duration and energy expenditure in the year prepregnancy and in early pregnancy (mean 15 weeks gestation). Regression models estimated mean differences in infant head circumference, birthweight, and ponderal index (birthweight/length3) across quartiles of pre- or early-pregnancy leisure time physical activity. We assessed effect modification by infant sex or prepregnancy overweight/obese status (BMI ≥ 25 kg/m2). Results: We observed positive associations between prepregnancy leisure time physical activity and head circumference overall and among male infants. Among males, each quartile increase in prepregnancy physical activity duration was associated with 0.14 cm (95% confidence interval = 0.046, 0.24; trend P = 0.004) greater head circumference. We did not observe associations between leisure time physical activity and birthweight or ponderal index overall. Each quartile increase in pre- or early-pregnancy physical activity duration was associated with 17–23 g lower birthweight among female infants and among women with normal prepregnancy BMI. Conclusions: We observed positive associations between prepregnancy leisure time physical activity and head circumference among male infants, and inverse associations of pre- and early-pregnancy physical activity with birthweight among female infants and women with normal prepregnancy BMI. Future studies should confirm results and elucidate mechanisms of observed associations.

Leisure Time Physical Activity and Gestational Diabetes Mellitus in the Omega Study.

PURPOSE Findings of studies investigating associations of leisure time physical activity (LTPA) with gestational diabetes mellitus (GDM) risk have been inconsistent. We investigated associations of LTPA with GDM and whether these associations differ by prepregnancy overweight/obese status or gestational weight gain category. METHODS Participants (N = 3209) of the Omega study, a pregnancy cohort study in Washington State (1996-2008), reported LTPA duration (h·wk) and energy expenditure (MET·h·wk) in the year before pregnancy and in early pregnancy. Diagnoses of GDM were abstracted from medical records. Poisson regression models were used to determine relative risks of GDM across tertiles of prepregnancy or early pregnancy LTPA duration and energy expenditure. Stratified analyses and interaction terms were used to assess effect modification by prepregnancy overweight/obese status (BMI ≥25 kg·m) or gestational weight gain category (adequate or excessive). RESULTS Each tertile increase in prepregnancy LTPA duration or energy expenditure was associated with 15% (95% CI = 0.72-1.00) and 19% (95% CI = 0.69-0.96) lower risk of GDM, respectively. Each tertile increase in early pregnancy LTPA duration or energy expenditure was associated with 16% (95% CI = 0.72-0.97) and 17% (95% CI = 0.72-0.95) lower risk of GDM, respectively. LTPA during both prepregnancy and early pregnancy was associated with a 46% reduced risk of GDM (95% CI = 0.32-0.89) compared with inactivity during both periods. LTPA-GDM associations were similar by prepregnancy BMI and gestational weight gain. CONCLUSION Our results support a role for the promotion of physical activity before and during pregnancy in the prevention of GDM.

Maternal healthy lifestyle during early pregnancy and offspring birthweight: differences by offspring sex

Abstract Purpose: Individual maternal lifestyle factors during pregnancy have been associated with offspring birthweight; however, associations of combined lifestyle factors with birthweight and potential differences by offspring sex have not been examined. Materials and methods: Participants (N = 2924) were identified from a pregnancy cohort in Washington state. Lifestyle factors during early pregnancy were dichotomized based on Alternate Healthy Eating Index score ≥62, leisure time physical activity (LTPA) ≥ 150 min/week, not smoking during pregnancy and Perceived Stress Scale score ≤3, then combined into a lifestyle score (0–4). Regression models were run overall and stratified by offspring sex, prepregnancy overweight/obese (BMI ≥25 kg/m2) and prepregnancy LTPA. Results: Overall, 20% of participants had healthy diet, 95% were nonsmokers, 55% had low stress levels, and 66% were physically active. Lifestyle score was not associated with birthweight (β = 3.3 g; 95% CI: −14.5, 21.0); however, associations differed by offspring sex (p = .009). For each unit increase in lifestyle score, there was a suggested 22.4 g higher birthweight (95% CI: −2.7, 47.6) among males and 14.6 g lower birthweight (95% CI: −39.9, 10.7) among females. Prepregnancy BMI and LTPA did not modify associations. Conclusions: Healthy lifestyle score in early pregnancy may be associated with greater birthweight among male offspring, but lower birthweight among female offspring.

A Pre-Pregnancy Biomarker Risk Score Improves Prediction of Future Gestational Diabetes

Abstract Context Previous studies have not examined the ability of multiple preconception biomarkers, considered together, to improve prediction of gestational diabetes mellitus (GDM). Objective To develop a preconception biomarker risk score and assess its association with subsequent GDM. Design A nested case-control study among a cohort of women with serum collected as part of a health examination (1984 to 1996) and subsequent pregnancy (1984 to 2009). Biomarkers associated with GDM were dichotomized into high/low risk. Setting Integrated health care system. Participants Two controls were matched to each GDM case (n = 256 cases) on year and age at examination, age at pregnancy, and number of pregnancies between examination and index pregnancy. Main Outcome Measure GDM. Results High-risk levels of sex hormone-binding globulin (SHBG; <44.2 nM), glucose (>90 mg/dL), total adiponectin (<7.2 μg/mL), and homeostasis model assessment-estimated insulin resistance (>3.9) were independently associated with 2.34 [95% confidence interval (CI): 1.50, 3.63], 2.03 (95% CI: 1.29, 3.19), 1.83 (95% CI: 1.16, 2.90), and 1.67 (95% CI: 1.07, 2.62) times the odds of GDM and included in the biomarker risk score. For each unit increase in the biomarker risk score, odds of GDM were 1.94 times greater (95% CI: 1.59, 2.36). A biomarker risk score including only SHBG and glucose was sufficient to improve prediction beyond established risk factors (age, race/ethnicity, body mass index, family history of diabetes, previous GDM; area under the curve = 0.73 vs 0.67, P = 0.002). Conclusions The improved, predictive ability of the biomarker risk score beyond established risk factors suggests clinical use of the biomarker risk score in identifying women at risk for GDM before conception for targeted prevention strategies.