Maternal smoking in pregnancy, fetal activity & newborn behavioral state: An observational ultrasound study

Maternal smoking during pregnancy (MSDP) remains one of the most common prenatal drug exposures in the US and worldwide. MSDP is associated with medical risk for the fetus and altered behavioral development in infants; however, fewer studies have examined the impact of MSDP on fetal behavior or newborn behavioral state. We investigated associations between MSDP and (a) fetal motor activity and (b) newborn behavioral state following handling. Participants were 79 healthy mother-fetus/newborn pairs (57% MSDP-exposed). MSDP was measured by maternal interview and verified by saliva biomarkers. Mothers completed an observational fetal ultrasound assessment between 24 and 37 weeks gestation (M = 28 weeks), including baseline, vibro-acoustic stimulus and recovery periods. Total fetal motor activity and complex body movements were coded from ultrasound videos. Following delivery, newborn post-handling behavioral state was assessed by direct observational coding. MSDP exposure was associated with higher baseline fetal motor activity, particularly at younger gestational ages. Further, motor reactivity to stimulation emerged at later gestational ages in MSDP-exposed fetuses, while motor reactivity was consistent across gestational ages in unexposed fetuses. Finally, heavy MSDP exposure was associated with more arousal following handling and greater need for soothing interventions in the newborn period. Monitoring of fetal behavior via ultrasound may offer a unique opportunity to identify at-risk infants and provides data for stronger public health messaging regarding risks of MSDP. Associations between MSDP and increased newborn fussiness highlight opportunities for education and anticipatory guidance in the postpartum period. •Investigated impact of maternal smoking on fetal motor activity and infant state•Smoking-exposed fetuses are more active at baseline.•Motor response to stimulation emerges later in gestation for exposed fetuses.•Exposed newborns show higher arousal and need more soothing after handling.•Ultrasound monitoring of fetal behavior may identify at-risk infants.