Incidence of spontaneous abortion among pregnancies produced by assisted reproductive technology

BACKGROUND: There has been increasing number of pregnancies following assisted reproductive technology treatment and their survival is understandably a matter of interest. The relative risk of spontaneous abortion in these pregnancies remains unclear. The objectives of this study were to quantify the relative risk in assisted reproductive technology pregnancies in relation to two cohorts of naturally conceived pregnancies and to assess the possible risk factors for spontaneous abortion among assisted reproductive technology pregnancies. METHODS: Three cohorts of pregnancies, 1945 pregnancies conceived following assisted reproductive technology treatment in a tertiary infertility clinic, 549 natural pregnancies in a prospective study of lifestyle and pregnancy (the Ford cohort), and 4265 pregnancies from another cohort (the Treloar cohort), were used in the study. RESULTS: After adjusting for age, the relative risk of spontaneous abortion was 1.20 (95% CI 1.03-1.46) in the assisted reproductive technology cohort in comparison with the Ford cohort. Within the assisted reproductive technology cohort, a history of spontaneous abortion predicted increased risk, while a low level of ovarian stimulation seemed to be related to a reduced risk. CONCLUSIONS: The study showed that the risk of spontaneous abortion was slightly increased in the assisted reproductive technology pregnancies after adjusting for maternal age and previous spontaneous abortion. Within the assisted reproductive technology cohort, several variables, including the level of stimulation, appeared to be linked with the risk of spontaneous abortion.