Alys Havard from the University of New South Wales and colleagues from five countries conducted a retrospective cohort study and concluded that taking the main drugs to help quit smoking in the first trimester of pregnancy does not increase the risk of major birth defects in the child. The analysis included all 5.2 million births that occurred from the beginning of 2001 to the end of 2020 in New South Wales, New Zealand, Norway and Sweden. Mothers of 9,325 newborns who smoked before pregnancy received nicotine replacement therapy in the first trimester, 3,031 received varenicline and 1,042 received bupropion. The results of the study were published in the journal JAMA Internal Medicine.
The study found that there was no significant association between the use of either drug and the overall risk of major congenital anomalies. Analysis of individual body systems revealed only a slightly increased risk of gastrointestinal defects with nicotine replacement therapy and urinary tract defects with varenicline. Given the harm caused by smoking, these results provide strong support for the advisability and safety of such drugs in the first trimester of pregnancy.