The mediating role of placenta in the relationship between maternal exercise during pregnancy and full-term low birth weight.

OBJECTIVE

To explore the association of maternal exercise during pregnancy with full-term low birth weight (FT-LBW) and whether placenta mediates their association.

STUDY DESIGN

We investigated 326 pregnant women delivering FT-LBW weight newborns (cases) and 1644 delivering full-term normal birth weight newborns (controls) in this case-control study. Information concerning maternal exercise during pregnancy, socio-demographics and obstetric characteristics were collected at Women and Children's Hospitals of Shenzhen and Foshan in Guangdong, China.

RESULTS

After adjusting for the potential confounders, maternal exercise frequency and duration during pregnancy were significantly negatively associated with FT-LBW, respectively. Moreover, compared with mothers taking no exercise during pregnancy, those taking exercises were significantly negatively associated with FT-LBW except those taking low/medium frequency and short duration exercise and high-frequency and long duration exercise, and their adjusted ORs ranged from 0.30 to 0.62. Furthermore, mediation analysis illustrated that placental weight partially mediated 27.20% of the association between maternal exercise frequency during pregnancy and FT-LBW, but not the association between maternal exercise duration during pregnancy and FT-LBW.

CONCLUSIONS

Maternal exercise during pregnancy is beneficial for lowering FT-LBW risk, especially when taking appropriate and enough exercise. Placenta weight partially mediates the association between maternal exercise frequency during pregnancy and FT-LBW.