Exposure to the smoking cessation medicine varenicline during pregnancy: a prospective nationwide cohort study.
OBJECTIVE
The purpose of this study was to investigate the extent of exposure to varenicline during pregnancy in 'real-life' post-marketing use and follow-up all pregnancy exposures to identify maternal and fetal outcomes.


METHODS
This was a prospective observational cohort study conducted in New Zealand using intensive prescription event monitoring methods. A nationwide cohort of patients dispensed varenicline during a 4-year period was established from pharmacy dispensing data. Women of reproductive age were followed up with specific questionnaires to identify exposure to varenicline during pregnancy and maternal and fetal outcomes.


RESULTS
Between 1 April 2007 and 31 March 2011, 23,721 patients were dispensed varenicline. Pregnancy questionnaires were sent for 6882 women of reproductive age, representing 29% all patients (54% female/unknown sex patients) in the varenicline cohort. The frequency of pregnancy exposure in women for whom a valid pregnancy questionnaire was returned was 23/2739 = 0.84%. For the 23 reports of pregnancy identified, exposure to varenicline was from the time of conception for 19 cases. Duration of exposure during pregnancy ranged from 1 day to 16 weeks. Adverse outcomes were identified in five of 17 live births: one baby had birth asphyxia and recurrent chest infections, one had gastro-oesophageal reflux, one was diagnosed with ankyloglossia and two had feeding difficulties.


CONCLUSIONS
This study suggests that approximately 1% of women of reproductive age prescribed varenicline may be exposed to this medicine during pregnancy. This could result in significant fetal exposure worldwide and indicates the need for a global pregnancy register for varenicline.
Intensive Medicines Monitoring Programme, New Zealand Pharmacovigilance Centre, Department of Preventive and Social Medicine, University of Otago Medical School, Dunedin, New Zealand.
Mira
M
Harrison-Woolrych
Helen
H
Paterson
Ming
M
Tan
D000293:Adolescent; D000328:Adult; D001552:Benzazepines / Q000009:adverse effects / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000139:chemically induced* / Q000453:epidemiology; D011446:Prospective Studies; D011810:Quinoxalines / Q000009:adverse effects / Q000627:therapeutic use*; D016540:Smoking Cessation; D011795:Surveys and Questionnaires; D013997:Time Factors; D000068580:Varenicline
D001552:Benzazepines; D011810:Quinoxalines; D000068580:Varenicline
pharmacoepidemiology; pregnancy exposure; smoking cessation; varenicline