Large prospective, pregnancy and infant follow-up trial assures the health of 1000 fetuses conceived after treatment with the GnRH antagonist ganirelix during controlled ovarian stimulation.

BACKGROUND A concern for new compounds in fertility treatment is the possible risk of perinatal complications or birth defects. To demonstrate long-term safety of ganirelix (GnRH antagonist) treatment in controlled ovarian stimulation (COS), follow-up data on pregnancy and neonatal outcome were analysed for 1000 fetuses (>or=16 gestational weeks). METHODS Obstetrical and neonatal data on 839 pregnancies, resulting in 969 live born infants after ganirelix treatment were compared with a historical cohort of 753 pregnancies after long GnRH agonist (buserelin) treatment, resulting in 963 live born infants. All treatment cycles were performed in a single fertility centre. The infants were examined at the Universitair Ziekenhuis Brussel using an identical follow-up protocol. Incidence of major malformations (i.e. causing functional impairment or requiring surgical correction) was the primary end-point and was analysed by logistic regression including treatment, age of mother, IVF method and pregnancy type (singleton/multiple) as independent variables. RESULTS There were no relevant differences in maternal characteristics, fertilization method and pregnancy and delivery complications between the ganirelix and historical GnRH agonist groups. There were relatively more multiple pregnancies in the historical GnRH agonist group (31.9%) than the ganirelix group (18.7%; P < 0.0001). The groups were comparable with respect to pregnancy loss after 16 weeks gestation. The incidence of major congenital malformations in fetuses with gestational age >or=26 weeks was 5.0% in the ganirelix cohort versus 5.4% in the historical GnRH agonist group (odds ratio 0.94, 95% confidence interval, 0.62-1.42). CONCLUSION In terms of neonatal outcome and risk of major malformations, treatment with the GnRH antagonist ganirelix during COS is as safe as traditional GnRH agonists.