Afternoon napping during pregnancy and low birth weight: the Healthy Baby Cohort study

Although afternoon napping is very common, particularly in China, there are limited data regarding the potential health effects of afternoon napping during pregnancy on perinatal outcomes. We aimed to investigate the relationship between afternoon napping during late pregnancy and low birth weight (LBW).

A total of 10,111 women aged 15-50 years were recruited from the ongoing Healthy Baby Cohort study in China, in 2012-2014. Information on sleep habits during pregnancy was obtained by questionnaires at the time of institutional delivery. Logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs).

Compared with women who reported no napping, the multivariate-adjusted ORs for LBW were 0.83 (95% CI 0.58-1.18) and 0.61 (0.44-0.83) for those who reported ≤1 h and >1 h of napping, respectively (P for trend <0.001). LBW risk reached a threshold at approximately 1.5 h of afternoon napping. The inverse relationship between afternoon napping during late pregnancy and LBW was stronger among women with lower educational level (P for interaction = 0.011). For frequency of afternoon napping, the multivariate analysis suggested a significant inverse association between LBW and napping 5-7 days/week (OR 0.68; 95% CI 0.50-0.92).

To our knowledge, this is the first study to estimate the association between afternoon napping and frequency of afternoon napping during late pregnancy and LBW risk. Our findings suggest that appropriate afternoon napping and frequency of afternoon napping for pregnant women might reduce the risk of LBW.