Physical activity during pregnancy and adverse birth outcome: a prospective cohort study in China.

The relationship between prenatal physical activity (PA) and adverse birth outcomes is still inconclusive. We aimed to investigate the association between PA during pregnancy and adverse birth outcomes by using data from the Guangxi Zhuang birth cohort (GZBC) in China. A total of 11,292 mother-infant pairs were included from GZBC in China. The information on PA status, intensity, adequacy, and volume and birth outcomes were collected. Multivariable linear and logistic regression models were applied to analyze the effects of PA during pregnancy on birth weight z-scores (BW z-scores) and gestational age and risk of small-for-gestational age (SGA) and preterm birth (PTB), respectively. Cubic spline analysis was conducted to detect a nonlinear dose-response of total weekly activity metabolic equivalents (MET) and birth outcomes. Compared to no regular PA during pregnancy, moderate and high-intensity PA (MVPA) was associated with increase BW z-scores ( = 0.08, 95%CI: 0.002, 0.15,  = .044) and associated with a marginal significant decrease in risk of PTB (OR = 0.73, 95%CI: 0.51, 1.05,  = .093). However, PA had no relationship with gestational age and risk of SGA, and Nonlinear relationships were not observed between total weekly activity MET and risk of SGA and PTB. These finding shows that PA during pregnancy may increase the BW z-score and reduce risk of PTB, supporting the guidelines that pregnant women should be encouraged to engage in appropriate physical activity during pregnancy in China.