Heavy Smoking During Pregnancy Linked to Greater Odds of Autism in Offspring

June 13, 2021

Lighter Smoking Habits Associated with Weaker Odds

A recently published study in the American Journal of Epidemiology examined the risk of autism spectrum disorder (ASD) in children born to mothers who smoked prior to and during their pregnancy. According to the research team responsible for this work, their study was the first in the United States to investigate maternal smoking during pregnancy in relation to ASD in offspring, considering intellectual disability comorbidity, in a statewide cohort including all births. The study’s results showed that the odds ratio for ASD with and without intellectual disability in the full cohort to be 1.15 for children born to women who smoked 3 months before/during pregnancy when compared to children born to non-smoking mothers. The odds ratio increased to 1.55 for children born to mothers who smoked at least 20 cigarettes a day in any trimester. The research team came to these results by analyzing all California births from 2007-2010 using the Office of Vital Statistics birth rolls. Cases of autism were identified by using records maintained by the California Department of Developmental Services (DDS) collected by the state’s 21 regional centers. The researchers then linked DDS case records to California birth records using child and parental identifiers (e.g., first/last name, birthdate and sex). In the end, 11,722 cases of autism were identified out of more than 2,000,000 births. According to a CDC report from 2014 on the prevalence of smoking during pregnancy in the United States, 10% of women smoked three months before pregnancy. Of those women, 24% quit before becoming pregnant. All in all, the report showed that only 8.4% of American mothers smoked at any time during their pregnancy. Which begs the question, why invest time, money and   effort to conduct this study? The smoking rate is low amongst pregnant mothers and the autism rate still continues to climb. Smoking cigarettes is bad for everyone, including fetuses. However, since the percentage of mothers who smoke during pregnancy is low, smoking could not be a major factor in autism causation or the autism epidemic.

Original Study Abstract

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