Is smoking in pregnancy an independent predictor of academic difficulties at 14years of age? A birth cohort study.

Background: Studies of the effects of maternal smoking during pregnancy have reported inconsistent findings in relation to measures of offspring cognitive functioning. Few studies, however, have examined learning outcomes in adolescents, as opposed to IQ.

Aim: To examine the association between maternal smoking during pregnancy and academic performance among adolescent offspring.

Study Design: Population-based birth cohort study.

Subjects: 7223 mothers and children were enrolled in the Mater-University of Queensland Study of Pregnancy in Brisbane (Australia) from 1981 to 1984. Analyses were restricted to the 4294 mothers and children for whom all information was reported at 14-year follow-up.

Outcome Measures: Reports of academic performance of 14-year-old offspring in English, Science and Mathematics with different patterns of maternal smoking (never smoked, smoked before and/or after pregnancy but not during pregnancy, or smoked during pregnancy).

Results: Low academic achievement was more common only in those whose mothers had smoked during pregnancy. Effect sizes were, however, small. The adjusted mean difference in total learning score for smoking before and/or after pregnancy but not during pregnancy, and for smoking during pregnancy were -0.18 (-0.58, 0.22) and -0.40 (-0.69, -0.12). Similarly, the adjusted odds ratios were 0.9 (0. 65, 1.24) and 1.35 (1.07, 1.70).

Conclusion: Maternal smoking during pregnancy is a preventable prenatal risk factor associated with small decrements in offspring academic performance that continue into adolescence.