Low use of varenicline and bupropion for smoking cessation during pregnancy

Maternal use of varenicline or bupropion for smoking cessation during pregnancy is low, but nicotine replacement therapy (NRT) is more common, according to a recent study published in JAMA Network Open.¹

Smoking has been reported in 6% to 18% of pregnant individuals and is associated with multiple adverse pregnancy and childhood outcomes. Smoking cessation in the first half of pregnancy reduces the risk of adverse outcomes but is achieved by under 50% of individuals who smoke.

One study reported an increased risk of asthma development in the first 7 years of life because of maternal smoking, with an adjusted odds ratio of 1.27 for any smoking.² Additionally, newborns of mothers who smoked over 10 cigarettes per day had an average reduced birthweight of 250 g.

Behavioral first line quit-smoking options for pregnant individuals include feedback, counselling, and peer-support.¹ However, smoking cessation pharmacotherapies such as varenicline, NRT, and bupropion are often more effective in a general population. Currently, data about the safety of these methods is lacking.

Investigators conducted a cohort study to evaluate the use of smoking cessation pharmacotherapies during pregnancy. Pregnancies resulting in live birth or still birth at 22 weeks’ gestation or later were eligible. Exclusion criteria included missing or invalid gestational age and the mother being an overseas visitor or immigrating during pregnancy.¹

Smoking cessation pharmacotherapies were determined using prescription medication dispensing databases. A treatment course during the gestation period indicated use of a smoking cessation pharmacotherapy during pregnancy, with the date of conception determined by subtracting gestational age from the date of childbirth.

Maternal smoking status was determined based on information in the perinatal or medical birth records and using an International Statistical Classification of Diseases and Related Health Problems, Tenth Revision code. A smoking indicator in the perinatal or inpatient record indicated the pregnant individual had a record of smoking.¹

Participants from New South Wales, Australia, New Zealand, and Sweden were included. Maternal characteristics included sociodemographic characteristics, year of childbirth, obstetric history, morbidities, smoking in early pregnancy, and quantity smoked in early pregnancy. Indigenous status was also included in Australia and New Zealand data.

There were 1,700,638 pregnancies included in the analysis, with 729,498 from individuals aged under 30 years and 118,690 including smoking during early pregnancy. Early pregnancy smoking was most common in New Zealand at 12.8% and least common in Norway at 3.4%.¹

Smoking cessation pharmacotherapy use during pregnancy ranged from 0.02% to 2.01%. For varenicline, the range was from 0.02% in Norway to 0.14% in New South Wales, for bupropion from under 0.01% in Norway and Sweden to 0.07% in New Zealand, and for prescription NRT from under 0.01% in Norway to 1.86% in New Zealand.

When limiting the analysis to smoking cessation pharmacotherapy use in pregnancies with maternal smoking, rates ranged from 0.33% to 12.25%, 0.26% to 1.25%, 0.03% to 0.39%, and 0.06% to 11.39%, respectively.¹

Varenicline was used during the first trimester in 89.6% to 99% of cases, but 25.5% to 47% were identified based on a single dispensing. For bupropion, first trimester use was reported in 76.9% to 89.9% of cases and 35.2% were identified based on a single trimester. These rates were 54.3% to 62% and under 10%, respectively, for NRT.

These results indicated low rates of varenicline and bupropion use during pregnancy, but that NRT prescription is more common. Investigators concluded research about the safety of these pharmacotherapies during pregnancy is warranted.¹

References

1. Robijn AL, Tran DT, Cohen JM, et al. Smoking cessation pharmacotherapy use in pregnancy. JAMA Netw Open. 2024;7(6):e2419245. doi:10.1001/jamanetworkopen.2024.19245
2. Jaakkola JJ, Gissler M. Maternal smoking in pregnancy, fetal development, and childhood asthma. Am J Public Health. 2004;94(1):136-40. doi:10.2105/ajph.94.1.136