Abnormal human chorionic gonadotropin (hCG) trends after transfer of multiple embryos resulting in viable singleton pregnancies.

Purpose: The purpose of this study is to investigate whether abnormal hCG trends occur at a higher incidence among women conceiving singleton pregnancies following transfer of multiple (two or more) embryos (MET), as compared to those having a single embryo transfer (SET).

Methods: Retrospective cohort study was performed of women who conceived singleton pregnancies following fresh or frozen autologous IVF/ICSI cycles with day 3 or day 5 embryo transfers between 2007 and 2014 at a single academic medical center. Cycles resulting in one gestational sac on ultrasound followed by singleton live birth beyond 24 weeks of gestation were included. Logistic regression models adjusted a priori for patient age at oocyte retrieval and day of embryo transfer were used to estimate the Odds Ratio of having an abnormal hCG rise (defined as a rise or < 66% in 2 days) following SET as compared to MET.

Results: Among patients receiving two or more embryos, 6.1% (n = 84) had abnormal hCG rises between the first and second measurements, compared to 2.7% (n = 17) of patients undergoing SET (OR 2.16, 95% CI 1.26-3.71). Among patients with initially abnormal hCG rises who had a third level checked (89%), three-quarters had normal hCG rises between the second and third measurements.

Conclusions: Patients who deliver singletons following MET were more likely to have suboptimal initial hCG rises, potentially due to transient implantation of other non-viable embryo(s). While useful for counseling, these findings should not change standard management of abnormal hCG rises following IVF. The third hCG measurements may clarify pregnancy prognosis.