Smoking cessation pharmacotherapies not linked to adverse pregnancy outcomes

Takeaway

• Pregnancy exposure to smoking cessation pharmacotherapies including bupropion, varenicline, and nicotine replacement therapy (NRT) was not associated with an increased risk for adverse birth outcomes.
• Varenicline was associated with a lower risk for adverse birth outcomes without major congenital anomalies, which was inconsistent with recommendations suggesting that NRT should be preferred over varenicline.

Why this matters

• Smoking cessation pharmacotherapies including varenicline, bupropion and NRT are more effective than behavioural cessation interventions in non-pregnant adults; however, limited data are available regarding their safety and efficacy in pregnancy.

Study design

• A population-based cohort study of 97,875 women who smoked during pregnancy.
• Of 97,875 women, 233, 330 and 1057 exposed to bupropion, NRT and varenicline, respectively, and 96,255 unexposed women.
• Primary outcomes: the risk for any adverse perinatal events at birth and major congenital anomaly.
• Funding: The Australian National Health and Medical Research Council.

Key results

• No significant difference was observed in the risk for any adverse perinatal events:
  • between bupropion-exposed and unexposed women (HR, 0.93; 95% CI, 0.73-1.19) and
  • NRT-exposed and unexposed women (HR, 1.02; 95% CI, 0.84-1.23).
• Varenicline-exposed vs unexposed women were significantly at a lower risk for any adverse perinatal events (HR, 0.86; 95% CI, 0.77-0.97).
• Varenicline-exposed vs unexposed women were less likely to have infant:
  • to be born premature (HR, 0.72; 95% CI, 0.56-0.92);
  • be small for gestational age (HR, 0.68; 95% CI, 0.56-0.83); and
  • have severe neonatal complications (6.6% vs 8.2%; HR, 0.74, 95% CI, 0.57-0.96).
• Varenicline-exposed women during the first trimester had a lower risk for major congenital anomaly (HR, 0.91; 95% CI, 0.72-1.15).
• Varenicline-exposed women were at a lower risk for adverse perinatal event compared with unexposed women (HR, 0.58; 95% CI, 0.33-1.05).

Limitations

• Outcomes such as pregnancy loss or termination <20 weeks were not examined.