Effect of blood pregnancy test time on IVF clinical outcomes in urine β-HCG-positive patients: A retrospective cohort study

Abstract Background To evaluate the optimal time of blood pregnancy test for urine beta-human chorionic gonadotropin (β-HCG)-positive patients following embryo transfer. Methods A total of 1,106 women who underwent embryo transfer between January 2019 and December 2019 were divided into three groups based on the time of positive pregnancy test at the hospital: the ≤ 9 days group (n = 355), the 10–12 days group (n = 598), and the ≥ 13 days group (n = 153). Clinical pregnancy ratio, ectopic pregnancy rate, multiple pregnancy rate, early miscarriage rate, late pregnancy loss rate, live birth ratio, preterm birth rate, very preterm birth rate, gestational week of delivery, and congenital malformation rate of the three groups were compared. Results The time preference for pregnancy test was 10 days among patients with D3 embryo transfer and 11 days among those with blastocyst transfer. Patients in the ≥ 13 days group were older and had a higher proportion of previous childbirth(s). Patients in the ≤ 9 days group had a higher live birth ratio and a lower risk of early miscarriage than the other two groups; similar results were seen in a sensitivity analysis that excluded women aged over 35 years and those with previous childbirth(s). Nevertheless, no differences were observed in the clinical pregnancy ratio, ectopic pregnancy rate, late pregnancy loss rate, very preterm birth rate, gestational week of delivery, or congenital malformation rate for all ranges of pregnancy test time. The pregnancy test time to predict the early miscarriage and live birth based on receiver operating characteristic (ROC) curve was day 9 after embryo transfer. After excluding women aged over 35 years or those with previous childbirth(s), the optimal time to conduct pregnancy test based on ROC curve was day 9 or 10 after embryo transfer in predicting early miscarriage, the pregnancy test time to predict live birth should be conducted on day 9 after embryo transfer. Conclusion Patients with positive results for urine β-HCG after embryo transfer should receive blood pregnancy test on day 9–10 after embryo transfer, which probably facilitated the optimization of live birth.