Associations between prenatal exposure to second hand smoke and infant self-regulation in a New York city longitudinal prospective birth cohort

Abstract

Background: Prenatal exposure to active or passive maternal smoking -also referred to as second hand smoke (SHS) exposure - are associated with externalizing behaviors, hyperactivity and attention deficit hyperactivity disorder, problems which derive in part from altered self-regulation.

Objectives: Determine the influence of prenatal SHS on infant self-regulation using direct measures of infant behavior in 99 mothers from the Fair Start birth cohort followed at the Columbia Center for Children's Environmental Health.

Methods: Self-regulation was operationalized with self-contingency, the likelihood of maintaining/changing behavior from second-to-second, measured via split-screen video recordings of mothers playing with their 4-month infants. Mother and infant facial and vocal affect, gaze-on/-off partner, and mother touch were coded on a 1 s time-base. Third trimester prenatal SHS was assessed via self-report of a smoker in the home. Weighted-lag time-series models tested conditional effects of SHS-exposure (vs. non-exposure) on infant self-contingency for eight modality-pairings (e.g., mother gaze-infant gaze). Individual-seconds time-series models and analysis of predicted values at t₀ interrogated significant weighted-lag findings. Because prior findings link developmental risk factors with lowered self-contingency, we hypothesized that prenatal SHSSHS would predict lowered infant self-contingency.

Results: Relative to non-exposed infants, those who were prenatally exposed to SHS had lower self-contingency (more variable behavior) in all eight models. Follow-up analyses showed that, given infants were likely to be in the most negative facial or vocal affect, those with prenatal SHS were more likely to make larger behavioral changes, moving into less negative or more positive affect and to alternate between gaze-on and off mother. Mothers who were exposed to SHS during pregnancy (vs. non-exposed) showed a similar, albeit less prevalent, pattern of larger changes out of negative facial affect.

Conclusion: These findings extend prior work linking prenatal SHS with youth dysregulated behavior, showing similar effects in infancy, a critically important period that sthe stage for future child development.

Keywords: Externalizing behavior; Infant behavior; Prenatal exposure; Second hand smoke; Self-contingency; Self-regulation.