Pregnant smokers reduce smoking subconsciously, according to NU study

Used cigarettes lying on snowy ground.

Daily file photo by Susan Du

A Northwestern Medicine study finds that pregnant smokers reduce their smoking, even before knowing that they were pregnant.

Cate Bikales, Reporter

Pregnant smokers reduced their smoking by an average of one cigarette per day before knowing they were pregnant, according to a Northwestern Medicine study published in October.

The study is the first to examine the impact of pregnancy on a person’s smoking behavior, as opposed to most studies that explore the impact of smoking on pregnancy.

“Ultimately, our goal is to figure out what part of being pregnant is actually driving that reduction,” said Norrina Allen, co-author and associate professor of epidemiology. “Once we do, we can identify new targets for intervention to reduce smoking and addiction during pregnancy.”

Principal investigator Dr. Suena Massey said in a University press release that it was previously thought that pregnant smokers mostly limited smoking because of a conscious desire to protect their babies. 

But the study contradicts this notion, she said.

All 416 of the study’s participants smoked about 10 cigarettes per day before becoming pregnant. After smoking less than one cigarette per day between conception and the date they realized they were pregnant, the participants dropped their smoking by an average of another four cigarettes per day. 

Patterns of decline in smoking frequency occurred regardless of whether pregnancies were planned or whether smokers quit, according to the study.

Laurie Wakschlag, Ph.D., co-author of the study and vice chair of scientific & faculty development, said it took the research team over a year to synthesize the paper’s research.

“It takes a village,” she said. “We had addiction psychiatrists, statisticians, professors and more. No one scientist could have achieved it by themself, it’s a team process to find the answer.”

The paper is one of few studies to “harmonize” two independent cohorts, Allen said.

Of the participants, 145 were women from the Midwest recruited between 2000 and 2005, and 271 were from the Mid-Atlantic and were recruited between 2006 and 2009. Information gathered from both groups of participants was used for analysis in the study. 

Massey suggested in the University press release that human chorionic gonadotropin levels may be tied to the participant’s decreased desire to smoke. 

But, further research is currently investigating other factors that may cause declines in smoking among pregnant people, according to Allen.

Dr. Clara Schroedl, an associate professor of medicine in pulmonary and critical care medicine, said any research into the effects of smoking is beneficial.  

“As a lung doctor and someone who cares for patients with tobacco dependence, I think that any additional research into the mechanisms of nicotine dependence, especially in a really high-risk population like pregnant women, is important,” Schroedl said.

She added that the medical field must broaden its perspective on nicotine addiction treatments, and that additional attention should be paid to other biological or psychological factors that might contribute to a person’s likelihood of quitting smoking.

Meanwhile, Allen said she hopes future research will illuminate more details regarding the timing of the decreased desire to smoke in pregnant people.

“It’s been really unthought of that pregnancy itself, not just the desire to protect the fetus, has been driving smoking reductions during pregnancy, but really, there’s a huge impact,” Allen said. “If it’s a biological process … that could have important implications for addiction (research) overall.” 

Email: [email protected] 

Twitter: @CateBikales

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