Rates of major congenital malformations were similar for both.

The dangers of smoking during preg­nancy are well known, but potential risks associated with smoking cessa­tion pharmacotherapies (i.e. nicotine replacement therapy, varenicline and bupropion) are less certain. Researchers used propensity score matching to compare rates of major congenital malfor­mations between 326,000 infants born to mothers who smoked cigarettes but received no smoking cessation prescrip­tions and infants born to mothers who were prescribed nicotine replacement therapy (9000 infants), varenicline (3000) or bupropion (1000) within 90 days of conception or during the first trimester. Data were drawn from population health registries in Australia, New Zealand, Norway and Sweden and comprised singleton live births between 2001 and 2020.

Key results were as follows:

• rates of major congenital malformations were not significantly different between the two groups of infants (risks, about 35 per 1000)
• for nicotine replacement therapy, the rates of major congenital malformations were similar whether long-­acting (e.g. patch) or short­-acting formulations were used
• in multiple sensitivity analyses, including those focused on potential misclassification of smoking status or nonuse of prescribed medications, no differences in malformation rates were noted.

Comment: These data can reassure patients who conceive while using these therapies that risks are no worse than smoking. Editorialists note that clinical trials support the efficacy of nicotine replacement therapy for smoking cessation in pregnancy but that efficacy trials are lacking for bupropion and varenicline in pregnancy; nevertheless, the safety data from this study can now inform decision making. I generally have been cautious, favouring behavioural strategies for smoking cessation during pregnancy, but I plan on incorporating these data into risk­benefit discussions.

Marie Claire O’Dwyer, MB BCh BAO, MPH, Clinical Assistant Professor in Family Medicine, University of Michigan Medical School, Ann Arbor, USA.

Tran DT, et al. Risk of major congenital malformations following prenatal exposure to smoking cessation medicines. JAMA Intern Med 2025 Mar 31; e-pub (https://doi.org/10.1001/jamainternmed.2025.0290).

Coleman T, Orton S. Using pharmacologic smoking cessation treatments in pregnancy. JAMA Intern Med 2025 Mar 31; e-pub (https://doi.org/10.1001/jamainternmed.2025.0278).

This summary is taken from the following Journal Watch titles: General Medicine, Women’s Health, Ambulatory Medicine, Pediatrics and Adolescent Medicine.