Heated tobacco product use in pregnancy associated with allergic disease in offspring
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Smoking heated tobacco products during pregnancy was associated with allergy — specifically asthma, rhinitis and conjunctivitis, and atopic dermatitis — in offspring, according to a study published in Allergy.
Although marketed as healthier alternatives to cigarettes, these products still present risks for women and their babies, Masayoshi Zaitsu, MD, PhD, professor and director, Center for Research of the Aging Workforce, University of Occupational and Environmental Health, Fukuoka, Japan, and colleagues wrote.
“The use of heated tobacco products (HTPs), in which tobacco leaves are heated to produce aerosols containing nicotine and hazardous chemicals, is an emerging concern, particularly among younger populations,” Zaitsu told Healio.
“The number of HTP smokers has increased globally, but no human study has assessed the adverse effects on the offspring of maternal use of HTPs during pregnancy so far,” Zaitsu said.
The web-based, cross-sectional survey generated responses from 5,688 pairs of postpartum women (mean age, 32 years; standard deviation [SD], 4.4) and infants (mean age, 0.9 years; SD, 0.5) born between July 2019 and August 2021.
According to the survey, 2.4% of the women smoked HTPs during pregnancy, including 2.3% who smoked during the first trimester and 1% who smoked during the second and third trimesters.
Also, 7.8% of the infants overall had been diagnosed with at least one of three allergic diseases, including asthma (1.2%), rhinitis/conjunctivitis (2.6%) and AD (5%).
Prevalence of these diseases tended to be higher among mothers classified as current smokers, who smoked the 3 months before (11.2%), during (15.2%) or after pregnancy (12.9%), or during the first (16.2%) or second and third trimesters (14.5%), with lower rates observed among mothers who never smoked (7.3%).
Researchers observed a significant association between current vs. never smokers of HTPs and prevalence of allergic diseases in infants (prevalence ratio [PR], 1.98; 95% CI, 1.28-3.05).
“The risk was double compared to that of the offspring of mothers who never smoked HTPs,” said Zaitsu.
This association was most pronounced with smoking during the first trimester (PR = 2.09; 95% CI, 1.37-3.21), and it was attenuated with smoking before pregnancy (PR = 1.48; 95% CI, 1.09-2.02) and after the infant was born (PR = 1.66; 95% CI, 1.01-2.72).
The researchers noted a similar pattern in subgroup analyses that excluded 163 current cigarette smokers during pregnancy and after birth, with significant associations during pregnancy (PR = 2.09; 95% CI, 1.18-3.68) and the first trimester (PR = 2.23; 95% CI, 1.27-3.92).
Further, the researchers found a 5% increase in allergy among infants (PR =1.05; 95% CI, 1.02-1.08) with each one-unit increase in daily maternal HTPs smoked during pregnancy, as well as a 122% increase in allergy prevalence (PR = 2.22; 95% CI, 1.28-3.88) with each one-unit increase in pack-year scale of HTP smoking during 3 months before pregnancy to birth.
Inflammatory processes and other complex biological mechanisms resulting from exposure to tobacco smoke during pregnancy increase allergy onset in offspring, the researchers wrote, adding that nicotine exposure during early life impairs lung growth and decreases lung function as well.
“HTPs are tobacco products and are likely associated with postnatal health risks,” Zaitsu said. “We found a benefit of quitting HTP use, with an over 50% decrease observed in the risk of mothers who quit HTP smoking before pregnancy.”
Although more studies on minimizing the risks of smoking HTPs is necessary, the researchers continued, there is an association between smoking during pregnancy and allergic diseases among infants, and pregnant women should quit.
“The genesis of allergic disorders has complex processes involving genes, host immune response, epithelial function and environmental dimensions,” Zaitsu said.
“However, similar to tobacco smoking, HTPs can be one of the preventable risk factors for allergic disorders,” he continued. “Thus, further research on minimizing HTP-related risks should be encouraged.”
Perspective
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These findings are not surprising to clinicians and researchers like me who know about the effects of cigarette smoking during pregnancy. This study confirms what we suspect is happening, that exposure to heated tobacco products during the prenatal period leads to higher risk for asthma and allergies in offspring.
In fact, we have suspected that heated tobacco products would increase the risk for these outcomes like actual cigarette smoking. This study confirms that.
Tobacco cessation is an important aspect of medical care for all patients. It is even more important for women who are planning on conceiving a child. The use of heated tobacco products as a substitute for cigarette smoking should be discouraged during pregnancy.
I suspect that heated tobacco products, like cigarette smoking, will have adverse effects on lung development in the offspring of these women. Identifying effects of prenatal exposure to heated tobacco products on lung function in the child should be investigated.
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