Assisted reproductive interventions and multiple birth

Objective: To investigate the contributions of ovulation-inducing drugs and assisted reproductive technologies to multiple birth. Methods: This historic prospective study was conducted in a cohort of 13,15 1 women who delivered after 20 weeks' gestation between October 1996 and De cember 1999. The study setting was a Colorado health maintenance organizati on. Cases were women who were pregnant as a result of exposure to treatment with either assisted reproductive technologies or ovulation induction in t he absence of assisted reproductive technologies. The main outcome measure was multiple birth. Results: There was a significant association between assisted conception an d multiple birth. Compared with women with naturally conceived pregnancies, there was a 25-fold likelihood (95% confidence interval 18, 35, P < .001) of multiple birth among women exposed to any of those treatments. In the to tal cohort the proportion of multiple births attributable to those treatmen ts was 33%. After adjusting for the use of assisted conception and other co variates, we found no association between advanced maternal age and multipl e birth. Conclusion: In this cohort, assisted reproductive interventions were strong ly associated with multiple birth. Although a higher proportion of older wo men sought assisted reproductive technologies, we did not find an independe nt relationship between advanced maternal age and multiple birth. The incre asing number of multiple births attributable to assisted conception raises public health concerns regarding multiple gestation-related maternal and in fant morbidities. (Obstet Gynecol 2001;97:195-200. (C) 2001 by The American College of Obstetricians and Gynecologists.).