Prenatal smoking and drinking are associated with altered newborn autonomic functions

BACKGROUND: Prenatal smoking and drinking are associated with SIDS and neurodevelopmental disorders. Infants with these outcomes also have altered autonomic nervous system (ANS) regulation. We examined the effects of prenatal smoking and drinking on newborn ANS function. METHODS: Pregnant women were enrolled in Northern Plains, USA (NP) and Cape Town (CT), South Africa. Daily drinking and weekly smoking data were collected prenatally. Physiological measures were obtained during sleep 12–96 hours post-delivery. RESULTS: 2,913 infants from NP and 4,072 from CT were included. In active sleep, newborns of mothers who smoked throughout pregnancy, compared to non-smokers, had higher breathing rates (2.2 breaths/min; 95% CI: 0.95, 3.49). Quit-early smoking was associated with reductions in beat-to-beat heart rate variability (HRV) in active (−0.08 sec) and quiet sleep (−0.11 sec) in CT. In girls, moderate-high continuous smoking was associated with increased systolic (3.0 mmHg, CI: 0.70, 5.24), and diastolic blood pressure (2.9 mmHg, CI: 0.72, 5.02). In quiet sleep, low-continuous drinking was associated with slower heart rate (−4.5 beat/min). In boys, low-continuous drinking was associated with reduced ratio of low-to-high frequency HRV (−0.11, CI: −0.21, −0.02). CONCLUSIONS: These findings highlight potential ANS pathways through which prenatal drinking and smoking may contribute to neurodevelopment outcomes.