A recent study reported a 2-year follow up of the effects of nicotine replacement therapy during pregnancy on infant developmental outcomes.
Smoking during pregnancy increases risk factors such as premature birth and birth defects, and is the leading cause of death in women and infants. In addition, smoking during pregnancy has been associated with infant developmental and behavioural problems, including attention deficit disorder. It is thought that stimulation of the nicotine receptors in the central nervous system at critical points during fetal development results in abnormal brain development. Studies on rats have demonstrated abnormal growth of neurons when given nicotine during pregnancy.
A recent study reported on nicotine replacement therapy during pregnancy as an alternative to smoking during pregnancy. Nicotine patches were assessed as a safer alternative to smoking during pregnancy, and possibly as a means of reducing fetal exposure to nicotine during important developmental time points, reducing the negative outcomes of smoking on both infant and mother. Termed the “SNAP” trial (Smoking and Nicotine in Pregnancy), this study compared nicotine patches with placebo in pregnant smokers. The initial short-term study found no safety issues, with adverse pregnancy and birth outcomes similar between the two groups.
The study was also the first to assess the long-term outcomes of nicotine replacement therapy during pregnancy in infants. The infants were followed up for 2 years after delivery. 1050 pregnant smokers took part in the study, between the ages of 16-45 years, who were 12-24 weeks pregnant. At the beginning of the study, the mothers were smoking at least 5 cigarettes per day. The study was carried out at 7 hospitals in England between May 2007 and February 2010. The mothers were randomly assigned to one of two groups. The first group, consisting of 521 participants, was given an 8 week course of nicotine patches (15mg/16h). The second group was the placebo group, consisting of 529 participants. Both groups received behavioural support for quitting smoking.
The study assessed scores of fine motor skills, gross motor skills, communication, problem solving, and social development in the 2 year old children. Results showed that 73% of infants in the nicotine replacement group had no impairment compared to 65% of the infants in the placebo group. The children born to women who were using nicotine patches during pregnancy were more likely to have survived without developmental delays compared to the women who were not using nicotine patches and continued smoking. Interestingly, the use of the nicotine patches did not affect the long-term quit rate of the women, however it temporarily doubled the quit rate during pregnancy. The study also assessed respiratory problems, however did not find any differences in the rate of respiratory problems in the children born to either women using nicotine patches or women who continued to smoke.
The authors suggest that the developmental results in the infants reflect a reduced exposure to nicotine in the nicotine replacement group. Due to the fact that most neurons develop in the first two trimesters of pregnancy, and additional brain development occurs between 24 weeks and term, reduced exposure during these crucial times may result in the reduced developmental delays. Evidence to support this comes from studies showing that smaller brain volume has been associated with fetal exposure to maternal smoking.
Although it is optimal for fetal nicotine exposure to be removed completely, the results of the study suggest that use of nicotine patches during pregnancy could provide an alternative to smoking that may have less of a detrimental effect on the child. However, it seems likely that more follow up studies should be conducted to confirm these results.
CDC Reproductive Health Fact Sheet “Tobacco Use and Pregnancy” Available from: http://www.cdc.gov/reproductivehealth/tobaccousepregnancy/Last Accessed: Aug 28, 2014.
Cooper, S,Taggar, J, Lewis, S, Marlow, N, Dickinson, A,Whitemore, R, Coleman, T. “Effect of nicotine patches in pregnancy on infant and maternal outcomes at 2 years: follow-up from the randomised, double-blind, placebo-controlled SNAP trial”The Lancet Respiratory Medicine, Early Online Publication, 11 August 2014. doi:10.1016/S2213-2600(14)70157-2
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Written by Deborah Tallarigo, PhD