Smoking during pregnancy may increase your baby’s chances of developing a variety of medical complications. Some research suggests a possible link between smoking during pregnancy and autism spectrum disorder (ASD).

ASD is a neurodevelopmental disorder, one of many conditions that affect your brain’s natural growth and development during early childhood. It’s present at birth, though years may pass before symptoms are noticeable.

Currently, there’s no single identifiable cause of ASD. Experts believe its underlying pathology involves a complex connection between genetics, environmental factors, and unexpected changes in the brain’s structure or function.

Smoking is one environmental factor that may affect a baby’s chance of developing ASD.

Smoking during pregnancy has not been conclusively proven to be a cause of ASD. Research on this topic is mixed, but a growing body of evidence points to a possible connection.

Language matters

You’ll notice we use the binary terms “mother” and “maternal” in this article to refer to the XX genetic contribution to a child and the term “father” to refer to the XY genetic contribution to a child.

While we realize this term may not match your gender experience, this is the term used by the researchers whose data was cited. We try to be as specific as possible when reporting on research participants and clinical findings.

The studies and surveys referenced in this article didn’t report data for or may not have had participants who are transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

Experts theorize that the toxic chemicals found in cigarettes and cigarette smoke could affect the chance of ASD by altering genetic expression and creating a toxic, low oxygen environment that affects typical growth and development of healthy brain tissue.

One study from 2024, for example, found maternal smoking during pregnancy increased the chance of ASD through three generations. This suggests that smoking may cause chemical changes in how genes express themselves that continue to get passed down from mother to child.

Other evidence, such as a 2022 study, suggests smoking might increase the likelihood a baby will develop ASD by compounding preexisting genetic risk factors in a mother. In other words, if you already have certain genetic predispositions for ASD, smoking could heighten those genetic factors.

The extent of the chance of ASD may also depend on how much a person smokes or the type of smoke exposure. Secondhand smoke, the exposure to cigarette smoke from another person, has been linked to a higher chance of ASD than maternal smoking alone.

For instance, a 2017 study found no significant relationship between maternal smoking and ASD, but ASD chance became significant when paternal smoking was also factored in.

A study from 2021 also found ASD chance was elevated by exposure to secondhand smoke from a father during pregnancy, particularly if the father smoked during the prenatal period.

While the research on maternal risk and ASD remains inconclusive, how much a mother smokes during pregnancy may play a role in ASD.

According to a 2020 study, for example, the chance of ASD was highest for children whose mothers smoked more than 20 cigarettes a day. Under that threshold, the association with ASD was much weaker.

Other studies, such as a 2018 study, have not found any conclusive evidence of a cause-and-effect relationship between maternal smoking during pregnancy and ASD or ASD-related traits.

More research is necessary before the exact relationship between ASD and smoking during pregnancy is clear.

Although the link between smoking during pregnancy and ASD isn’t clear, smoking has been conclusively linked to other conditions, such as:

Research also suggests smoking during pregnancy may have a connection to other neurodevelopmental conditions, like attention deficit hyperactivity disorder (ADHD).

The underlying causes of ASD aren’t fully understood, but other factors during pregnancy may increase a baby’s chances of developing ASD.

According to a review from 2022, maternal factors during pregnancy that may increase the likelihood of ASD include:

Some research also notes children have a higher chance for ASD when their mothers have asthma.

Risk factors are not a guarantee that a baby will develop ASD, though. Children can be born with ASD even if their mothers have no risk factors, and some mothers with many risk factors have babies that never develop ASD.

Resources to stop smoking

To find assistance with smoking cessation, consider contacting the following resources:

What happens if you smoke while pregnant?

There’s no way to know how smoking while pregnant will affect your baby, but smoking has been linked to multiple health complications like stillbirth, low birth weight, and sudden infant death syndrome.

What if you can’t quit smoking during pregnancy?

If you can’t quit smoking while pregnant, seek professional guidance. Working with your doctor to find a solution can help you reduce the risks to your baby as soon as possible. Your doctor can help you find counseling services and nicotine replacement therapy options and can monitor your health and the health of your baby.

Not everyone who smokes while pregnant experiences complications. Your personal outcomes will depend on individual factors like your age, overall health, and any underlying medical conditions.

According to the current position statement from the American College of Obstetricians and Gynecologists, smoking during pregnancy is associated with:

  • 5% to 8% of preterm births
  • 13% to 19% of low birth weights
  • 22% to 34% of SIDS
  • 5% to 7% of preterm infant death

The exact link between smoking while pregnant and ASD isn’t clear. More research is necessary to draw conclusions.

Some evidence suggests smoking may increase the chance of ASD by altering genetic expression and creating a toxic environment that affects brain tissue development.

How much you smoke, personal genetic predispositions, and exposure to secondhand smoke may all play an important role in ASD development related to smoking.