Can early -human chorionic gonadotropin predict birth of singletons and twins after in vitro fertilization?

Objective: To assess the predictive value for clinical pregnancy outcome of -hCG level at 13d after embryo transfer.Methods: Retrospective study of IVF clinical pregnancies diagnosed at 6 weeks. We calculated the value of -hCG level at 13d after embryo transfer to predict live births.Results: We analyzed 177 IVF cycles between 2009 and 2014 (50 singleton births, 50 twin births, 27 sets with a vanishing twin, 43 first trimester singleton pregnancy loss and seven first trimester total twin pregnancy loss). Singleton pregnancies with a -hCG concentration<85 mIU/mL had an 89% risk of having a first trimester loss whereas a concentration>386mU/mL had a 91% chance of a live birth. Twin pregnancies with a concentration<207 mIU/mL had only a 33% chance of delivering twins and a 55% risk of having a vanishing twin; whereas a level>768 mIU/mL was associated with a 81% chance of live twin birth and a low risk (19%) of having a vanishing twin. Age, type and duration of infertility, body mass index (BMI) and number of fertilized oocytes did not affect these calculations.Conclusions: -hCG level at 13d after embryo transfer might predict outcomes in clinical singleton and twin pregnancies following IVF.