ADHD after fetal exposure to maternal smoking

Area of Science:

• Reproductive Health
• Child Development
• Psychiatric Epidemiology

Background:

• Maternal smoking during pregnancy is linked to a 2-4 fold increased risk of ADHD in offspring.
• Genetic and socioeconomic factors may confound this association.
• Investigating the direct impact of prenatal smoking exposure on ADHD risk is crucial.

Purpose of the Study:

• To examine the association between maternal smoking during pregnancy and ADHD in offspring.
• To control for genetic and socioeconomic confounding factors.
• To clarify the independent risk posed by prenatal smoking exposure.

Main Methods:

• A Swedish population-based register study of 982,856 children (6-19 years old).
• Logistic regression analyzed ADHD medication odds ratios (ORs) associated with maternal smoking.
• A within-mother, between-pregnancy design adjusted for genetic confounding in 26,292 mothers.

Main Results:

• Maternal smoking (>=10 cigarettes/day) showed an OR of 2.86 (2.66-3.07) for ADHD medication in the general population.
• After adjusting for genetic factors using a within-subjects design, the OR decreased significantly to 1.26 (0.95-1.58).

Conclusions:

• A strong association exists between maternal smoking during pregnancy and offspring ADHD in Sweden.
• The observed association is substantially explained by shared genetic and socioeconomic factors.
• The independent risk of ADHD from prenatal smoking exposure alone appears to be considerably lower than initially suggested.