Nicotine replacement therapy during pregnancy and infantile colic in the offspring.

OBJECTIVE To investigate the associations between use of nicotine replacement therapy (NRT) and smoking during pregnancy and infantile colic in the offspring. METHODS We used data from maternal interviews (from pregnancy and at 6 months post partum) from the Danish National Birth Cohort (1996-2002). We included 63 128 live-born singletons with complete information on nicotine exposure during pregnancy and infantile colic symptoms as recorded at 6 months of age. RESULTS A total of 46 660 infants (73.9%) were unexposed to nicotine during pregnancy; 207 (0.3%) were exposed to NRT, 15 016 (23.8%) were exposed to smoking, and 1245 (2.0%) to both. A total of 4974 (7.9%) infants fulfilled Wessel's modified criteria for infantile colic. Prenatal nicotine exposure was associated with elevated risk for infantile colic in the offspring. Compared with the unexposed, NRT users had an adjusted odds ratio (OR) (95% confidence interval) of 1.6 (1.0-2.5; P = .03), smokers had OR = 1.3 (1.2-1.4), and women who both smoked and used NRT had OR = 1.6 (1.3-1.9). Partners' smoking was not associated with infantile colic after adjustment for maternal smoking. CONCLUSIONS We corroborated the association between smoking and infantile colic after adjustment for several possible confounders in a large cohort study. Moreover, we found that infants exposed to NRT prenatally had an increased risk for infantile colic of the same magnitude as those exposed to tobacco smoke. Thus, nicotine may play a role in the pathogenesis of infantile colic.