Prevention of intellectual impairment in children of women who smoke cigarettes during pregnancy

Abstract

Objective: To analyze the influence of a comprehensive program of nurse home visitation on the intellectual functioning of children born to women who smoked cigarettes during pregnancy.

Design: Randomized clinical trial. Treatment 1: sensory and developmental screening at ages 1 and 2 years; treatment 2: screening plus free transportation for prenatal and well-child care; treatment 3: screening, transportation, plus prenatal home visitation; treatment 4: screening, transportation, prenatal home visitation, plus postnatal home visitation through the children's second birthdays.

Setting: Semi-rural community in Upstate New York.

Participants: 400 families in which the mothers registered before the 30th week of pregnancy and had no previous live births. Eighty-five percent of the mothers were either teenagers, unmarried, or poor. Analysis was limited to whites, who constituted 89% of sample.

Intervention: Nurse home visitation during pregnancy (treatments 3 and 4) or during pregnancy and the first 2 years of the child's life (treatment 4). During pregnancy, the nurses helped women improve their health-related behaviors, informal social support, and linkage with needed community services.

Main findings: Children born to women who smoked 10 or more cigarettes per day at registration during pregnancy and who were assigned to treatments 3 and 4 had IQs (averaging across the 3rd and 4th years of life) that were 4.86 (95% CI: 0.47, 9.26) points higher after adjustment for covariates than did children born to women who smoked 10+ cigarettes per day and who were assigned to treatments 1 and 2. The positive influence of the home-visiting program on reducing the harmful effect of smoking appears to be due to prenatal visitation.

Conclusion: Comprehensive prenatal home-visitation services can offset the impairment in intellectual functioning associated with substantial maternal smoking during pregnancy.