Sleep patterns and the risk of adverse birth outcomes among Chinese women

Objective To evaluate the association between sleep patterns (sleep duration or timing) in late pregnancy and adverse birth outcomes (preterm delivery or small for gestational age, SGA). Methods An analysis of data from a prospective cohort study of pregnant women in Wuhan city, Hubei Province, China, between 2012 and 2014. Preterm delivery was defined as delivery before 37 gestational weeks. SGA was defined as neonatal birthweight below the 10th percentile of the predicted birthweight distribution. Results In total, 11 192 women were included in the analysis. After adjustment for potential confounders, 9.1-10 hours of nocturnal sleep was associated with a lower likelihood of SGA (odds ratio [OR], 0.81; 95% confidence interval [CI], 0.66-0.99) as compared with 7.1-9 hours. As compared with intermediate mid-sleep time (between 02:46 and 04:00), early mid-sleep time (at or earlier than 02:45) was associated with a higher likelihood of preterm delivery (OR, 1.64; 95% CI, 1.28-2.10). Conclusion Among a large cohort of pregnant Chinese women, 9.1-10 hours of nocturnal sleep was associated with a lower risk of SGA, whereas early mid-sleep time was associated with a higher risk of preterm delivery.