“Infants spent less time sleeping overall and woke up from naps sooner when their mothers smoked prior to breastfeeding,” says lead author Julie A. Mennella, PhD, a psychobiologist at the Monell Chemical Senses Center in Philadelphia.
Fifteen nursing mothers and their babies were monitored on days when the mothers smoked and on days when they did not. On smoking days, the women were allowed 20 minutes to smoke in another room just before breastfeeding. Some had just one cigarette while others had two or three.
The level of sleep disruption was directly related to the dose of nicotine infants received from their mothers’ milk, consistent with a role for nicotine in causing the sleep disruptions.
The findings, published in the journal Pediatrics, raise new questions regarding whether nicotine exposure through breast milk affects infant development.
While many women quit or cut down on smoking while pregnant, they often relapse following the birth of the baby. Mennella comments, “Because nicotine is not contraindicated during lactation, mothers may believe that smoking while breastfeeding will not harm their child as long as the child is not exposed to passive smoke. However, there has been very little research on either short- or long-term effects of nicotine delivered through breast milk.”
Additional studies are needed to examine the long-term developmental effects of nicotine delivered through breast milk, Mennella said.