Maternal smoking during pregnancy and newborn neurobehavior: effects at 10 to 27 days

To examine effects of maternal smoking during pregnancy on newborn neurobehavior at 10 to 27 days.

Participants were 56 healthy infants (28 smoking-exposed, 28 unexposed) matched on maternal social class, age, and alcohol use. Maternal smoking during pregnancy was determined by maternal interview and maternal saliva cotinine. Postnatal smoke exposure was quantified by infant saliva cotinine. Infant neurobehavior was assessed through the NICU Network Neurobehavioral Scale.

Smoking-exposed infants showed greater need for handling and worse self-regulation (P < .05) and trended toward greater excitability and arousal (P < .10) relative to matched, unexposed infants (all moderate effect sizes). In contrast to prior studies of days 0 to 5, no effects of smoking-exposure on signs of stress/abstinence or muscle tone emerged. In stratified, adjusted analyses, only effects on need for handling remained significant (P < .05, large effect size).

Effects of maternal smoking during pregnancy at 10 to 27 days are subtle and consistent with increased need for external intervention and poorer self-regulation. Along with parenting deficits, these effects may represent early precursors for long-term adverse outcomes from maternal smoking during pregnancy. That signs of abstinence shown in prior studies of 0- to 5-day-old newborns did not emerge in older newborns provides further evidence for the possibility of a withdrawal process in exposed infants.