Serum human chorionic gonadotropin concentration for predicting multiple gestation in pregnancies conceived with superovulation and intrauterine insemination

Assisted reproductive technologies are associated with an increased incidence of multiple gestation. Because they provide precise information on the time of ovulation, those technologies afford an opportunity to analyze the association between multiple gestation and maternal serum human chorionic gonadotropin (hCG) concentrations during early pregnancy. We retrospectively evaluated this association in 76 pregnancies (26 multiple) conceived with superovulation and intrauterine insemination. Using multiple linear regression, we discerned that the number of fetuses surviving the first trimester was directly proportional to the log of the hCG concentrations. The mean +1 SD for the estimated hCG values of singleton pregnancies was selected a priori as the threshold for detecting multiple pregnancies. This threshold value provided a sensitivity of 73%, specificity of 80% and overall accuracy of 78%. Nine of 11 pregnancies with three or more fetuses had hCG concentrations above the threshold values. Although there is a positive correlation between the number of fetuses surviving the first trimester and the hCG concentration early in pregnancy, the predictive value of the hCG concentration is useful only for excluding most triplet and quadruplet pregnancies.