Prenatal tobacco smoke exposure and neurological impairment at 10 years of age among children born extremely preterm: a prospective cohort

Objective To determine the association between prenatal tobacco smoke exposure and neurological impairment at 10 years of age among children born extremely preterm (<28 weeks of gestation). Design The Extremely Low Gestational Age Newborn (ELGAN) Study, a prospective cohort. Setting Ten-year follow-up of extremely preterm infants born at 14 US hospitals between 2002 and 2004. Methods Prenatal tobacco smoke exposure was defined as a mother's report at enrolment of active (i.e. maternal) and passive smoking during pregnancy. Poisson regression with generalized estimating equations was used. Models adjusted for mother's age, race/ethnicity, education, insurance, pre-pregnancy body mass index, US region, multiple gestation and infant's sex; and in sensitivity analysis, gestational age at delivery and clinical subtype of preterm birth, given their classification as intermediate and non-confounding variables. Main outcomes Neurological impairment at 10 years, epilepsy, cerebral palsy and cognitive impairment. Results Of 1200 ELGAN study survivors, 856 were assessed at 10 years of age with neurological outcomes, of whom 14% (118/856) had active tobacco exposure during pregnancy and 24% (207/852) had passive tobacco exposure. Compared with children who were not exposed prenatally to tobacco, children exposed to active tobacco use during pregnancy had a higher risk of epilepsy (14% versus 5%; adjusted relative risk: 1.68, 95% CI 1.45-1.92). This risk remained after adjustment for gestational age at delivery and clinical subtype of preterm birth. Prenatal tobacco smoke exposure was not associated with other assessed neurological outcomes, including cerebral palsy and multiple measures of cognitive impairment. Conclusions Among children born extremely preterm, prenatal active tobacco smoke exposure was associated with an increased risk of epilepsy at 10 years of life. Tweetable abstract Among infants born before 28 weeks of gestation, prenatal active tobacco smoke exposure was associated with an increased risk of epilepsy at 10 years of life.