Study: Smoking during Pregnancy Not Linked to Autism

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Exposure to certain environmental factors during pregnancy have been linked to a higher risk of autism birth, including exposure to chemicals, but researchers say that smoking isn’t one of them.

The link between smoking and autism has been up for debate for quite some time. In some studies, researchers believed that mothers who smoked were at a higher risk for delivering an autistic child. Other studies contradicted this theory and found no link between autism and smoking. The most recent study was one of the latter, and according to the researchers who participated in the study, the debate is now over.

“We found no evidence that maternal smoking during pregnancy increases the risk of autism spectrum disorders,” stated Dr. Brian Lee, lead author of the study, assistant professor at Drexel University and epidemiologist at Drexel’s School of Public Health. “Past studies that showed an association were most likely influenced by social and demographic factors such as income and occupation that have associations with both the likelihood of smoking and with the rate of autism spectrum disorders.”

These factors were accounted for in Dr. Lee’s Swedish-based study in which national and regional Swedish registries of 3,958 children with autism and 38,983 children without autism were compared. All children included in the study were born around the same time period.

At first, the study did suggest a slightly higher risk of autism in mothers who smoked – 19.8 percent of children with autism were exposed to prenatal smoking compared to 18.4 percent of children with autism that were not exposed. After adjustment for socio-demographic factors, such as income level, occupation and education level, however, the numbers evened out and there was no notable difference between the percentages of children diagnosed with autism in each group.

Mothers should know, however, that the aim of the study wasn’t to excuse smoking during pregnancy. Instead, it was meant as a way to rule out, as stated by Dr. Lee, “another suspect on the list of possible environmental risk factors for ASD.” Smoking during pregnancy has been linked to many other health complications, including:

  • Decreased fetal growth
  • Low birth weight
  • Placental abruption (a condition in which the placenta, responsible for providing nourishment to the fetus, separates from the uterine wall)
  • Premature birth
  • Miscarriage
  • Still birth
  • Sudden infant death syndrome (more than 18% of all SIDS infants are linked to maternal smoking during pregnancy).

It is advisable that all women discontinue smoking before trying to conceive. If conception happens without notice, an effective plan for quitting smoking should be implemented.

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About the Author

Kate Givans is a wife and a mother of five—four sons (one with autism) and a daughter. She’s an advocate for breastfeeding, women’s rights, against domestic violence, and equality for all. When not writing—be it creating her next romance novel or here on Growing Your Baby—Kate can be found discussing humanitarian issues, animal rights, eco-awareness, food, parenting, and her favorite books and shows on Twitter or Facebook. Laundry is the bane of her existence, but armed with a cup of coffee, she sometimes she gets it done. Find out more about Kate’s books at

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