Sex-specific associations between feto-placental growth and maternal physical activity volume and sitting time: Findings from the Queensland Family Cohort study

Antenatal physical activity (PA) is associated with beneficial changes in placental growth and function; however, the effect of excessive sitting time is less clear. The aim of this study was to investigate whether feto-placental growth changes with maternal activity, and whether these associations differ in a sex-specific manner. This study included women enrolled in the Queensland Family Cohort study who self-reported PA and sitting time at 24 or 36 weeks of gestation. Placental growth factors and feto-placental growth parameters at delivery were analysed by PA volume and sitting time, as well as by fetal sex. Women who reported excessive sitting time during mid-pregnancy and had a female fetus showed higher placental PlGF (p = 0.031) and FLT1 (p = 0.032) mRNA expression with no difference in placental size at delivery. For the male, excessive sitting time during mid-pregnancy was associated with a lower placental weight (p = 0.001) and placental surface area (p = 0.012) and a higher birthweight to placental weight (BWPW) ratio (p = 0.042), with no change in placental growth factors. Moderate volume PA during mid-pregnancy was associated with lower VEGFA mRNA expression in the male placenta (p = 0.005) and a higher abdominal circumference in the female neonate (p = 0.042), with no overall difference in placental weight or birthweight for either sex. The results of this study suggest that mid-pregnancy may be an important timepoint for programming of feto-placental growth in relation to maternal activity. Our findings highlight the independent benefits of reducing sitting time during pregnancy, particularly for women carrying male fetuses. •Maternal physical activity and sitting time are associated with sex-specific differences in feto-placental growth parameters.•Mid-pregnancy is an important timepoint for the programming of placental growth in relation to maternal activity.•Excessive maternal sitting time appears to have a greater effect on the growth of the placenta than physical activity.