TUESDAY, Sept. 4 (HealthDay News) -- Nicotine in breast milk disrupts
babies' sleep patterns and shortens naps by one third, according to a new study,
"Infants spent less time sleeping overall and woke up from naps sooner when
their mothers smoked prior to breast-feeding," lead author Julie A. Mennella, a
psychobiologist at the Monell Chemical Senses Center, said in a prepared
statement.
Text Continues Below
Writing in the September issue of Pediatrics, Mennella and colleagues argued
that these results should lead to further research on the impact of nicotine on
infant development. Many women who quit smoking during pregnancy begin again
while breast-feeding their infant, the researchers said.
"Because nicotine is not contraindicated during lactation, mothers may believe
that smoking while breast-feeding 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,"
said Mennella.
The study team measured the feeding and sleeping patterns of 15 breast-fed
infants over three and a half hours on two separate days. The infants were
between 2 months and 7 months old. All the mothers were current smokers who had
abstained from smoking for at least 12 hours before the observation periods.
The mothers smoked one to three cigarettes before one of the observation periods
and didn't smoke anything before the second period. On both occasions, the
mothers breast-fed their infants on demand during the observation period.
Following each feeding, the mothers laid the infants down in a cot or on the
floor.
An actigraph on the babies' ankles allowed researchers to monitor sleep and
activity. Levels of nicotine and cotinine, a byproduct of nicotine processed by
the body, were measured in breast milk samples provided by the mothers before
each feeding.
Babies whose mothers smoked before the observation period napped for 53 minutes
compared to 84 minutes of napping among babies whose mothers did not smoke. The
37 percent reduction in total sleep time was due to a shortening of the longest
nap and to reductions in the amount of time spent in both active and quiet
sleep.
Researchers noted that the infants consumed the same amount of breast milk
during each observation period, suggesting that they accepted the tobacco
flavoring of the milk.
Previous research by Mennella's team had shown that nicotine levels peak in
breast milk 30 minutes to 60 minutes after smoking one to two cigarettes and are
gone after three hours, suggesting that mothers can time their smoking and
breast-feeding opportunities. Additional research is needed to fully understand
the impact of nicotine on infant development, Mennella said.
