Early β-hCG levels predict live birth after single embryo transfer

Purpose Specific serum beta human chorionic gonadotropin (beta-hCG) parameters that can predict live birth after an embryo transfer have yet to be defined. Methods We performed a retrospective cohort study of 1,028 patients with a detectable beta-hCG who underwent a single embryo transfer between 2002 and 2019 at a large academic center. Two beta-hCG parameters were examined in relation to live birth: 1) "doubling" defined as beta-hCG doubling over 48 h and 2) "reaching 100" defined as a beta-hCG >= 100 mIU/mL by 15 days after oocyte retrieval (AOR). Results One thousand three hundred forty cycles involving a single embryo were analyzed. Two thirds were frozen embryos and 86% were blastocyst transfers. Preimplantation genetic testing was performed in almost 30% of cycles. When beta-hCG levels "doubled," a live birth occurred in 80.7% of cycles and when beta-hCG levels "reached 100" by 15 days AOR, live birth occurred in 81.6% of cycles. When beta-hCG levels both doubled and reached 100 by 15 days, AOR 85.4% cycles resulted in live birth. A multiple logistic regression model to control for patient and cycle level factors revealed a live birth odds ratio (OR) of 8.0 (95% CI 5.7-11.1) when beta-hCG "doubled" and an OR of 21.2 (95% CI 14.3-31.5) when beta-hCG "reached 100." When both these latter parameters were met, the OR was 12.5 (95% CI 8.9-17.8). Conclusion beta-hCG parameters of "doubling" and "reaching 100" by 15 days AOR are robust predictors of live birth and can aid in patient counseling regarding pregnancy outcomes soon after single embryo transfer.