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Association between seven-day serum β-hCG levels after frozen–thawed embryo transfer and pregnancy outcomes: a single-centre retrospective study from China

Citation

Sun, Zhengao et al. (2020), Association between seven-day serum β-hCG levels after frozen–thawed embryo transfer and pregnancy outcomes: a single-centre retrospective study from China, Dryad, Dataset, https://doi.org/10.5061/dryad.8931zcrnj

Abstract

Objective: Early monitoring of plasma human chorionic gonadotropin (β-hCG) level is vital in predicting pregnancy outcome. This study investigated the predictive value of serum β-hCG level on the 7th day after frozen-thawed embryo transfer (FET) for ongoing pregnancy (OP) and adverse pregnancy (AP).

Design: Retrospective study

Setting: The Reproductive and Genetic Center of the Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China.

Participants: 1,061 pregnant women who underwent FET between January 2014 and January 2017.  

Primary and secondary outcome measures: Pregnancy outcome.

Results: Serum β-hCG levels on the 7th day after FET were higher in the single OP group compared to the biochemical pregnancy (BP) group (p 0.001). Besides, the serum β-hCG cutoff level at 4.34 mIU/mL on the 7th day showed high predictive value (area under the curve [AUC] = 0.852). Serum β-hCG levels on the 7th day after FET were higher in the twin OP group compared to the single OP group (p0.001). Also, the serum β-hCG cutoff level at 17.95 mIU/mL on the 7th day showed high predictive value (AUC = 0.903). Serum β-hCG levels on the 7th day after FET were lower in the ectopic pregnancy (EP) group compared to the single OP group (p 0.001) whereas, serum β-hCG cutoff level at 4.53 mIU/mL on the 7th day exhibited a high predictive value (AUC = 0.860). Further, the serum β-hCG levels on the 7th day after FET were lower in the single early spontaneous abortion (SA) group compared to the single OP group (p0.001) while the serum β-hCG cutoff level at 5.34 mIU/mL on the 7th day exhibited high predictive value (AUC = 0.738).

Conclusion: Serum β-hCG on the 7th day after FET has good clinical significance for the prediction of OP and AP.

Methods

Patient and public involvement
This study was designed without patient participation, they were not invited to contribute to the study design and to develop patient-relevant outcomes or interpret the results. Also, patients did not contribute to the writing or editing of this document for readability or accuracy.

Assisted pregnancy method
The replacement cycle was adopted to prepare the endometrium at our center. The study participants were administered with Progynova (four tablets per day) for 5 days, starting 2-4 days after the first day of the last menstrual cycle. Progesterone was administered when the endometrial thickness was 8 mm to induce the transformation of the endometrium to the secretory phase. Thereafter, the patient was prepared for FET. We routinely provided 14 days of luteal support after FET irrespective of pregnancy. For patients with ongoing pregnancy, progynova and progesterone were continued for 10 weeks of gestation, and after confirming the presence of the fetal heart, the dosage was gradually reduced.

Measurement of serum β-hCG
At 7 and 14 dpt, venous blood was collected at 8:00–9:00 AM and centrifuged. β-hCG was measured from the collected serum via chemiluminescence. 

Grouping criteria for pregnancy outcomes
BP refers to serum β-hCG > 5 mIU/mL after FET but with no gestational sac. Ultrasound examinations were performed on the 35th day after FET to detect the fetal heartbeat, which was defined as a clinical pregnancy. The pregnancy outcome was classified as a normal pregnancy or adverse pregnancy (AP). Further, normal pregnancy was classified as either single or twin OP. The single OP refers to a single pregnancy with normal fetal development verified through obstetrical and ultrasound examination on or after the 12th gestational week. Twin OP refers to twin pregnancy exhibiting normal fetal development, which was verified through obstetrical and ultrasound examination on or after the 12th gestational week. AP included EP, BP, and single SA. EP refers to the presence of an extrauterine mass but without a gestational sac in the uterus. Early SA refers to natural spontaneous abortion before the 12th gestational week.

Funding

National Natural Science Foundation of China, Award: 81874484