Longitudinal Changes in Physical Activity during Pregnancy: NICHD Fetal Growth Studies.

Overview

abstract

INTRODUCTION: Exercise in pregnancy is associated with many perinatal benefits, but patterns of home, work, and commuting activity are not well described. We investigated longitudinal activity in singleton and twin pregnancy by activity domain and maternal characteristics. METHODS: In the NICHD Fetal Growth Studies cohorts, 2778 women with singleton and 169 women with twin gestations reported activity using the Pregnancy Physical Activity Questionnaire at up to 6 or 7 study visits, respectively. Metabolic equivalent of task (MET)-hours/week was calculated from reported activity. Baseline measurements (obtained between 10-13 weeks) reflected past year activity. Linear mixed models estimated MET-hours/week by domain (household/childcare, occupational, inactive, transportation, sports/exercise), self-reported race/ethnicity (Non-Hispanic White, Non-Hispanic Black, Hispanic, Asian/Pacific Islander), pre-pregnancy body mass index (BMI; <25, 25- < 30, ≥30 kg/m2), parity (0, ≥1), baseline activity (quartiles), and plurality (singleton, twin). RESULTS: Household/caregiving activity made up the largest fraction of reported MET-hours/week at baseline (42%), followed by occupational activity (28%). Median summed activity declined 47%, from 297 to 157 MET-hours/week, between 10 to 40 weeks, largely driven by changes in household/caregiving (44% decline), and occupational activity (63% decline). Sports/exercise activity declined 55% but constituted only 5% of reported MET-hours/week at baseline. At baseline, non-Hispanic Black women reported significantly higher activity than non-Hispanic White or Hispanic women, but differences did not persist across pregnancy. Across gestation nulliparous women reported significantly lower activity than parous women. Women with singleton gestations reported significantly more activity than women with twins from weeks 26-38. Baseline activity level was strongly associated with later activity levels. CONCLUSIONS: Measuring domains of activity beyond exercise, and collecting longitudinal measurements, is necessary to fully describe activity in diverse populations of pregnant women.