Heavy smoking in mothers linked to ASD in offspring

Smoking at least 20 cigarettes daily during pregnancy appears to put infants at risk of developing autism spectrum disorders (ASD), as shown in a study.

The study used data from a state-wide population-based cohort and sibling comparison design involving 2,015,104 participants. Researchers examined data on maternal smoking, demographics, and pregnancy.

In total, 11,722 children (74.4 percent boys) were diagnosed with ASD. Mothers of kids with ASD were on average older, more educated, and less frequently identified as Latina/Hispanic compared with mothers of kids without the neurodevelopmental condition.

On logistic regression analysis, maternal smoking was associated with an increased risk of ASD in the offspring. Compared with nonsmoking, smoking 3 months before or during pregnancy conferred a 15-percent risk increase (adjusted odds ratio [aOR], 1.15, 95 percent confidence interval [CI], 1.04–1.26) while heavy prenatal smoking (≥20 cigarettes/day in any trimester) conferred a 58-percent risk increase (aOR, 1.58, 95 percent CI, 23–101). The estimated risk related to 1–19 cigarettes/day was weaker.

On further analysis, the association between prenatal ever smoking and ASD risk in kids was evident among mothers with (aOR, 1.12, 95 percent CI, 0.84–1.49) or without (OR, 1.15, 95 percent CI, 1.04–1.27) intellectual disability.

In the sibling comparison, the risk estimates associated with heavy smoking were similarly elevated, but the CIs were wide.