Leisure-time physical activity during pregnancy and offspring size at 18 to 24 months.

Background: Leisure-time physical activity (LTPA) during pregnancy has maternal benefits, but effects on offspring have not often been considered. This study aimed to determine associations among trimester-specific LTPA during pregnancy and toddler size.

Methods: Women (n = 300) were recruited while pregnant in 2006. At follow-up (2008), women reported demographics; recalled type, duration, and frequency of trimester-specific LTPA (MET·min/wk); and rated their toddler's current LTPA level (more, same, or less than others their age). A subset (n = 23) volunteered to have maternal and toddler height, weight, and body fat measured. Maternal body mass index (BMI) and toddler weight-for-height z-scores (WHZ) were calculated.

Results: Median toddler WHZ was 0.6 (range -0.5 to 2.9). In Spearman correlations, third trimester LTPA was marginally associated with lower toddler weight (rs = -0.39, P = .06) and WHZ (rs = -0.40, P = .06), but no other measures of maternal LTPA and toddler body size were related. Birth weight z-score was positively associated with toddler weight (rs = 0.51, P = .01) but negatively associated with percent body fat (rs= -0.46, P = .03). Measures of maternal size were unassociated with toddler size.

Conclusions: These results provide preliminary support for LTPA during late pregnancy to have a lasting effect on offspring size.