Smoking in Pregnancy May Cause Antisocial Behavior in Kids

Pam Harrison

July 13, 2017

Children born to mothers who smoke during pregnancy (MSP) are at heightened risk of engaging in antisocial behavior during adolescence and adulthood – an effect that is likely causal, new research shows.

"Most children exposed to maternal smoking in utero will not go on to experience significant levels of antisocial behavior because their mothers smoked," Angela Paradis, ScD, Brown University School of Public Health, Providence, Rhode Island, told Medscape Medical News.

"Yet, given that maternal smoking during pregnancy remains prevalent among certain subgroups — teenage mothers, mothers with less than a high school education, for example — removing this exposure may have substantial impacts at the population level," she added.

The study was published online July 10 in the Journal of Epidemiology and Community Health.

Conduct Disorder

Participants in the study included the offspring of mothers enrolled in the Collaborative Perinatal Project (CPP), which was a study conducted in Boston, Massachusetts, and Providence, Rhode Island, between 1959 and 1966.

The CPP was a multicenter study that investigated prenatal and perinatal factors that affect mental, neurologic, and physical abilities of offspring.

A total of 3828 participants from the Providence, Rhode Island, site of the original CPP took part in the juvenile part of the current analysis as well as a separate adult analysis. The adult analysis involved a search of police records for criminal behavior at the age of 18 years and again in adulthood at the age of 33 years.

In total, 1684 adults from both Providence and Boston CPP sites were formally interviewed to determine the presence of antisocial behavior traits during adolescence and adulthood. The average age of the participants was 39 years at the time they were interviewed.

To assess for the presence of antisocial behavior during adolescence, investigators used the conduct disorder (CD) module of the Composite International Diagnostic Interview.

It was determined that participants had a history of antisocial behavior if they reported three or more symptoms of CD.

For adults, self-reported antisocial behavior was assessed using the antisocial personality disorder module of the Diagnostic Interview Schedule for DSM-IV.

"Of note, 59.0% of the offspring were exposed to MSP; 33.8% had mothers who smoked ≥1 pack/day," the investigators note.

The researchers examined the association between maternal smoking during pregnancy and antisocial behavior in offspring with regard to several types of effects. These included between-family effects and within-family effects, as well as estimated effects using the combined, weighted average of the other two estimates.

This statistical approach allowed investigators to better isolate the effect of maternal smoking from other factors, such as a history of mental health problems and low levels of education, which can influence the development of antisocial behavior.

Long-term Impact

Using this approach, in a fully adjusted model, the researchers found that maternal smoking during pregnancy did influence the development of various forms of antisocial behavior during adolescence.

"A one pack-a-day increase in MSP was associated with a 30% increased odds...of having ≥3 CD symptoms and an overall increase in CD symptoms," the researchers write.

Dr Paradis also notes that maternal smoking was treated linearly as a continuous variable. Thus, the effects of a one-pack-a-day in MSPs could be compared to effects associated with mothers who smoked one pack a day but who did not smoke during pregnancy, or the effects in mothers who smoked two packs a day could be compared in those who smoked one pack a day.

Participants whose mothers smoked during pregnancy were 25% more likely to report engaging in aggressive behavior during adolescence (odds ratio (OR) = 1.25).

In a fully adjusted model, the same pack-a-day increase in maternal smoking during pregnancy increased the likelihood that adults would meet three or more criteria for antisocial personality disorder (OR, 3.48).

For adults, the likelihood of engaging in nonaggressive antisocial behavior associated with mothers who had a pack-a-day increase in smoking during pregnancy was similar (OR, 3.21).

"A pack-a-day increase in MSP was associated with a 2.34-fold increased odds of having a record of non-violent juvenile offences...and more than doubled the odds of an adult violent offence," the researchers point out.

"Mothers in this study were enrolled between 1959 and 1966, most prior to the landmark surgeon general's report on the health consequences of smoking, so it is unlikely many women in this study were counseled by their physicians to quit smoking," Dr Paradis said.

"Findings from this study, while not definitive, suggest another reason why pregnant mothers should not smoke — it may negatively impact their children's behavior into adulthood," she added.

However, Dr Paradis pointed out that for women who quit smoking during pregnancy, there is a likelihood of returning to the habit after the baby is born. Thus, more is required than physicians simply telling women why smoking during pregnancy may be harmful.

"Women need to be supported in their efforts to quit and linked with services, including therapy," said Dr Paradis. She cautioned that the efficacy and safety of the use of products such as nicotine replacement during pregnancy are still largely unknown.

Negative Consequences

Commenting on the findings for Medscape Medical News, Marie Cornelius, PhD, emeritus associate professor of psychiatry and epidemiology, University of Pittsburgh School of Medicine, in Pennsylvania, noted that offspring who are exposed to cigarette smoke in utero are at increased risk for negative outcomes regarding many aspects of growth and behavior.

"The results from this well-designed prospective study extend previous findings of increased behavioral problems in exposed offspring," said Dr Cornelius.

In her own work, Dr Cornelius and colleagues found that prenatal exposure to cigarette smoke had adverse outcomes on behavioral dysregulation in offspring as early as age 6 years.

They also found that the relationship between maternal smoking during pregnancy and externalizing behaviors continued into adolescence and young adulthood. Young adults who had been exposed to cigarette smoke in utero were not only more like;y to smoke but were also more likely to have a history of arrests than young adults who had not been exposed.

"The Paradis et al study of adults in their 30s further underscores the long-term effects of maternal smoking during pregnancy and neurobehavioral effects with thoughtful control of potentially confounding factors," Dr Cornelius added.

The authors and Dr Cornelius have disclosed no relevant financial relationships.

J Epidemiol Community Health. Published online July 10, 2017. Abstract

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