The application of single beta-human chorionic gonadotropin (β-hCG) level measurement in women undergoing single blastocyst transfer.

We previously explored the associations between β-hCG on the 14th day post-embryo transfer (ET) and reproductive outcomes and established a series of cutoff values to predict different outcomes. The aim of this study was to explore the parameters associated with β-hCG levels and establish β-hCG cutoff values in women undergoing single blastocyst transfer. The patients were transferred with either fresh or frozen-thawed blastocysts. Serum β-hCG levels were compared among different groups. Cutoff values of β-hCG were established and applied to divide the patients into different groups, among which the β-hCG groups were compared. Develop day negatively affected β-HCG levels in those who were pregnant or gave live birth (P < 0.001, 0.008). Inner cell mass significantly affected β-hCG levels in women who were pregnant or gave live birth (P = 0.013, 0.044). Trophectoderm significantly affected β-hCG levels in women with most reproductive outcomes, except biochemical pregnancy (BP) (P = 0.184). The cutoff values of β-hCG for predicting positive outcomes were 194.1, 503.0, 1048.0, and 2590.5 mIU/L. BP rates and adverse pregnancy outcome rates were significantly lower in the higher β-hCG groups (P < 0.001). Shorter gestational age and lower birth weight and length (P = 0.005, 0.041, 0.003) were observed in the lowest-concentration β-hCG group. The application of a single β-hCG measurement was sufficient to predict reproductive outcome in women undergoing blastocyst transfer, under the full consideration of blastocyst parameters. However, the association between β-hCG and obstetric outcomes remains to be investigated and fully explained.