Dual Neonatal Neurobehavioral Dimensions Following Prenatal Cigarette Exposure - Abstract
Maternal cigarette-smoking during pregnancy adversely impacts neonatal neurological integrity with far ranging developmental consequences. Neurobehavioral assessment scales have shown increased behavioral excitabilityin newborn infants with prenatal cigarette-exposure (PCE), suggesting dose-response signs of stress/abstinence. In contrast to increased excitability, depressant effects of PCE have been found on fetal heart rate variability (HRV) and power spectra of heart rate rhythms. This study further examined the utility of analyses of HRV to detect effects of PCE on neurobehavioral integrity in newborn infants. Participants were 51 term infants who varied by maternal report in the amount of cigarette-use per day during pregnancy: 10 infants with Mild Exposure (ME, <10 cigarettes/day), 15 infants with Moderate/Heavy exposure (MHE, >10 cigarettes/day) and 26 Non-Exposed (NE) comparison infants. Infant heart rate was time-sampled every 5 seconds for 15 minutes and subjected to standard, previously used methods of spectrum analysis. Analyses of Co-Variance with the amount of maternal marijuana and alcohol use during pregnancy statistically controlled found significant dual dimensions of effects of PCE on several measures of HRV and power spectra. Infants with ME showed lower heart rate variability and power of spectral peaks than NE infants; infants with MHE showed greater heart rate variability and power of spectral peaks than NE infants. Whereas lower HRV and spectral peaks of ME infants may reflect depressant effects of mild hypoxic-ischemia, the higher HRV and spectral peaks of MHE infants may reflect excitatory effects of withdrawal that supersede effects of hypoxia.