Maternal smoking during pregnancy and sleep problems in 2-month-old infants

Objective

The study aimed to assess possible association between maternal smoking during pregnancy and sleep disturbances in 2-month-old infants.

Subjects and methods

The study comprised 200 apparently healthy infants from community settings selected by chance (88 boys, 112 girls), aged 2 months, who were singletons born in St. Petersburg in 2007. The mothers were asked to complete the questionnaires addressing major infant, maternal and demographic characteristics with particular emphasis on maternal smoking during pregnancy. As a part of the interview, the mothers were requested to describe possible sleep disturbances in their infants, divided into five major sleep domains: bedtime problems, excessive daytime sleepiness, awakenings, regularity and duration of sleep as well as snoring.

Results

Of 200 mothers, 63 (31.5%) smoked during pregnancy. The babies born to smoking mothers more commonly were reported as having bedtime problems [odds ratio (OR)=2.75; 95% confidence interval (CI)=1.15–6.58], and this association remained significant after adjustment was made for major potential confounders. Maternal smoking after delivery did not significantly add to the risk. Babies born to smoking mothers more often had irregular sleep, but this association was markedly influenced by the confounding effect of maternal education. No statistically significant differences were found for total night time sleep duration, the frequency of night time awakenings, excessive night time waking and daytime sleepiness as well as for snoring and noisy breathing during sleep.

Conclusion

Maternal smoking during pregnancy should be considered as a risk factor for infant bedtime problems, emerging as early as 2 months of age.