Introduction
Neonatal birth weight, which is related to perinatal morbidity and mortality,1–4 is affected by several obstetric complications, including preterm births (PTB), fetal growth restriction (FGR), and preeclampsia.5,6 Specifically, birth weight <1,500 g, defined as very low birth weight, is affected by severe prematurity and leads to increased mortality.7Additionally, small for gestational age (SGA) infants have also been associated with neonatal and post-neonatal mortality.4,8,9 Further, LBW and SGA are associated with increased risk of coronary artery disease, diabetes mellitus, and arterial hypertension in adult life, as described in the Baker hypothesis,10 which has been revised to the concept of developmental origins of health and disease (DOHaD).11Conversely, macrosomia, defined as birth weight >4,000 g, is also associated with a risk of morbidity in infants.2,12
Several modifiable factors, including maternal pre-pregnancy body weight, gestational maternal body weight gain (BWG), and diet, have a major impact on the neonatal birth weight.5,12–14Similarly, maternal sleep duration (MSD) during pregnancy also affects obstetric outcomes.15–17 However, the association between MSD and neonatal birth weight remains unclear.15,18 Previous studies have reported reduced MSD as a risk factor for SGA,19,20 but Morokuma et al. reported no association between MSD and SGA in a study including 8,631 participants.21 Moreover, the appropriate MSD required to prevent LBW, SGA, and macrosomia has not been elucidated. As sleep is often disturbed in pregnant women,15 appropriate MSD would be a great concern for pregnant women.
The present study evaluated the effect of MSD on neonatal birth weight using the data from a nationwide Japanese prospective birth cohort study.