Smoking During Pregnancy and Autism

For at least the last 50 years, public health officials have been warning pregnant women not to smoke. Lower birth weight, higher infant mortality, and negative health consequences in young offspring were found in women who smoked throughout their pregnancies.

Since autism spectrum disorder (ASD) diagnoses in young children have increased in recent decades, researchers have naturally looked at any effect smoking may have on the development of the disorder. The causes of autism are still being studied, and environmental, genetic, and biological risk factors have been linked to it, according to the Centers for Disease Control and Prevention (CDC).

What is Autism?

According to the CDC, autism spectrum disorder (ASD) is classified as a developmental disability, and scientists believe there are many causes. It generally appears before the age of three years, and the symptoms and abilities of people with ASD vary widely. While some people with ASD are nonverbal and remain dependent on caregivers, others can live and work quite independently. Because autism is a spectrum disorder, the level of dysfunction varies from very mild to severe, and a child can fall into any level in between.

Some of the most common symptoms of ASD include an inability to connect with people or make eye contact, problems socializing, cognitive deficiencies and repetitive behaviors.

Symptoms of Autism

Other symptoms include:

• Delayed language
• Delayed cognitive or learning skills
• Difficulty judging the emotions of others and responding accordingly
• No facial expressions by nine months
• Unusual reactions to sounds, tastes, smells, or touching objects
• Obsessions

Behavioral and developmental cues, which can vary widely from person to person, are relied on to make a diagnosis. Early diagnosis and treatment are important for addressing the individual’s needs.

Does smoking play any role in the development of autism?

The jury is still largely out on whether smoking plays a role in the development of autism. But there have been studies done not only on mothers smoking during pregnancy but also second-handed exposure to smoking as well as whether grandmaternal smoking during a mother’s pregnancy. Let’s take a look at some of the results.

Peer-reviewed research studies of possible links between cigarette smoking during pregnancy and developmental disorders like Autism Spectrum Disorder:

• A study in Paedatric and Perinatal Epidemiology of infants born in Finland between 1987 and 2005 showed a modest increased risk of pervasive developmental disorder (PDD), which is a subtype of ASD in which the patient displays mild symptoms of ASD, or meets some but not all of the criteria for an ASD diagnosis when a mother smokes. The study found no correlation between maternal smoking and or Asperger’s syndrome (which is a high-functioning autism that is now under the umbrella of ASD). The study also noted six other population-based studies on maternal smoking that gave contradictory results.¹
• A study in the journal Autism examined prenatal exposure to father’s smoking in relation to ASD. Noting the worldwide prevalence of ASD and the critical period of baby’s development during pregnancy, researchers concluded that paternal smoking during the mother’s pregnancy “increases risk for having a child at high likelihood for ASD.” The study went on to report that the risk can be reduced by as much as 11-15 percent, and encouraged education and intervention to reduce smoking during family planning and pregnancy.²
• A study in Scientific Reports looked at mothers and fathers whose own mothers smoked during pregnancy and whether their offspring were at greater risk for having children who develop ASD. The detailed analysis looked at data surrounding several traits associated with autism, such as reduced social communication, speech coherence, and sociability, as well as repetitive behaviors. It found an association between maternal grandmothers’ smoking during pregnancy and certain ASD traits in granddaughters. It did not find an association between paternal grandmothers’ smoking and ASD traits in grandchildren.³
• Scientists at the University of Bristol, acknowledging that the incidence of ASD has increased over the years, found a 53% increase in ASD diagnoses in grandchildren if the maternal grandmother smoked during pregnancy. In addition, 67% of granddaughters showed traits linked to ASD if their maternal grandmother smoked during pregnancy. Interestingly, the researchers say these results suggest that the eggs of a developing female in the womb could be affected by maternal smoking but further research is needed.⁴

Treatments for Autism Spectrum Disorder (ASD)

If your child is diagnosed with ASD, addressing concerns and seeking help early on is key. According to the CDC, there are many approaches that can be taken to ensure the best possible outcomes for your child and your family. Each child diagnosed with ASD has unique challenges and symptoms, therefore treatments are highly individualized, and are multifaceted, running the gamut from behavioral and developmental therapies to educational and social and relational interventions. The Early Start Denver Model (ESDM) is particularly geared toward children 12-48 months old and uses play, social situations and natural settings to address all developmental areas in which the child is behind. There is also a book written for parents: An Early Start for your Child with Autism.

Early intervention is the key to the treatment of Autism

If you suspect your child may have ASD, talk to your doctor about your concerns. Please remember that no one is to blame, but early intervention can help immensely. Many specialists work with babies, children, and adults, offering treatments and therapies ranging from developmental to educational, social, and behavioral. There are many resources available including books, support groups, and well-trained and experienced doctors who have been treating patients with ASD for years. You do not have to do this alone, and waiting could mean your child will not receive the care they need to thrive.

Further investigation is needed into the connections between cigarette smoking and autism spectrum disorder.

There have been relatively few studies done on the relationship between smoking and autism, and further studies are needed. No matter the results, the National Child Development Study (NCDS) reports maternal smoking is “bad for the baby” overall. In addition to lower birth weights and higher levels of infant mortality, children whose mothers smoked had lower cognitive abilities than their peers, and consequences followed them into adulthood. Educational campaigns have made a difference — the CDC reports that only 5.5 percent of births in 2020 were to women who smoked, a big decrease from previous years.⁷

^{[1] Smoking during pregnancy and risk of autism spectrum disorder in a Finnish National Birth Cohort. Tran PL, Lehti V, Lampi KM, Helenius H, Suominen A, Gissler M, Brown AS, Sourander A., Paediatr Perinat Epidemiol. 2013 May;27(3):266-74. doi: 10.1111/ppe.12043. PMID: 23574415; PMCID: PMC3652271..}

^{[2] Prenatal exposure to paternal smoking and likelihood for autism spectrum disorder. Autism. Kim B, Ha M, Kim YS, Koh YJ, Dong S, Kwon HJ, Kim YS, Lim MH, Paik KC, Yoo SJ, Kim H, Hong PS, Sanders SJ, Leventhal BL., 2021 Oct;25(7):1946-1959. doi: 10.1177/13623613211007319. Epub 2021 Apr 20. PMID: 33878952; PMCID: PMC8419001..}

^{[3] “Grand-maternal smoking in pregnancy and grandchild’s autistic traits and diagnosed autism.” Golding, Jean, et al., Scientific reports 7.1 (2017): 1-14.}

^{[4] Grandmaternal smoking in pregnancy and grandchild’s autistic traits and diagnosed autism. Golding, J. et al., Scientific Reports, 2017 DOI: 10.1038/srep46179.}

^{[5] Early Start Denver Model website..}

^{[6] National Child Development Study, Smoking During Pregnancy..}

^{[7] Centers for Disease Control and Prevention, Smoking and Tobacco Use, Current Cigarette Smoking Among Adults in the United States (March 17, 2022).}

^{[8] A Systematic Review of the Link Between Autism Spectrum Disorder and Acetaminophen: A Mystery to Resolve, interpreting data from Parker SE, Collett BR, Werler MM: Maternal acetaminophen use during pregnancy and childhood behavioural problems: Discrepancies between mother- and teacher-reported outcomes. Paediatr Perinat Epidemiol. 2020, 34:299-308. 10.1111/ppe.12601).}

^{[9] Paracetamol use during pregnancy—a call for precautionary action, Bauer, A.Z., Swan, S.H., Kriebel, D., Liew, Z., Taylor, H.S., Bornehag, C.G., Andrade, A.M., Olsen, J., Jensen, R.H., Mitchell, R.T. and Skakkebaek, N.E., 2021. Nature Reviews Endocrinology, 17(12), pp.757-766..}

^{[10] A Systematic Review of the Link Between Autism Spectrum Disorder and Acetaminophen: A Mystery to Resolve, interpreting data from Parker SE, Collett BR, Werler MM: Maternal acetaminophen use during pregnancy and childhood behavioural problems: Discrepancies between mother- and teacher-reported outcomes. Paediatr Perinat Epidemiol. 2020, 34:299-308. 10.1111/ppe.12601)..}

^{[11] Paracetamol use during pregnancy—a call for precautionary action, Bauer, A.Z., Swan, S.H., Kriebel, D., Liew, Z., Taylor, H.S., Bornehag, C.G., Andrade, A.M., Olsen, J., Jensen, R.H., Mitchell, R.T. and Skakkebaek, N.E., 2021. Nature Reviews Endocrinology, 17(12), pp.757-766.}