Risk factors for high-order multiple implantation after ovarian stimulation with gonadotrophins: evidence from a large series of 1878 consecutive pregnancies in a single centre.

Abstract

High-order multiple pregnancies (triplets or more) have a large adverse impact on perinatal morbidity and mortality as well as important economic consequences. Most triplets and higher births are due to ovulation induction alone or in combination with intrauterine insemination (IUI) rather than to in-vitro fertilization (IVF). The present investigation was undertaken to determine whether there were specific variables that related to patient clinical characteristics (age of the woman, duration of infertility, type of infertility, body mass index, basal FSH and LH concentrations), treatment characteristics (initial dose of gonadotrophins, total dose of gonadotrophins administered, number of days of ovarian stimulation, insemination procedure, number of spermatozoa inseminated in patients undergoing IUI, type of luteal support), and ovarian response (oestradiol serum concentrations, number and size of follicles) that might be associated with the occurrence of high-order multiple implantation in order to develop a prediction model. This study employed univariate, multivariate and receiver-operating characteristic (ROC) analysis of a large series of 1878 consecutive pregnancies obtained in cycles stimulated with gonadotrophins. Of them, 1771 (94.3%) were low-order pregnancies (1477 singletons and 294 pairs of twins) and 107 (5.7%) were high-order pregnancies. Predictive variables in the multivariate analysis were age of the woman, serum oestradiol concentrations and number of follicles >10 mm on the day of HCG injection. Stratification of the number of follicles into three categories (1 to 3, 4 to 5, and >5 follicles respectively), peak serum oestradiol and woman's age according to the ROC curves, showed that the risk of high-order multiple implantation correlated significantly with increasing total number of follicles and was significantly increased in women with a serum oestradiol >862 pg/ml and aged < or =32 years. This three-variable model can help to identify patients at high-risk for high-order multiple pregnancy in ovulation induction cycles.