Serum HCG 12 days after embryo transfer in predicting pregnancy outcome

Assisted reproduction treatment (ART) entails a risk of ectopic pregnancy and early pregnancy loss. Serum HCG has been found to be predictive of pregnancy outcome. Our aim was to assess the clinical value of a single early HCG assay in ART pregnancies taking into account the aetiology and treatment of infertility.

During 1994-1999, we studied 774 embryo transfer cycles resulting in pregnancy defined as a serum HCG concentration of > or =5 IU/l on day 12 following embryo transfer. The treatment included IVF in 518, ICSI in 119, and frozen embryo transfer in 137 cycles. Serum HCG concentrations were measured by fluoroimmunometric assay. Pregnancies were classified as viable (live fetus at > or =22 weeks gestation) or non-viable (biochemical pregnancy, miscarriage, ectopic pregnancy and molar pregnancy). Data on the outcomes were retrospectively retrieved from the records.

The median HCG concentration was 126 IU/l in viable pregnancies and 31 IU/l in non-viable pregnancies (P < 0.0001). The median HCG concentration was 115 IU/l in singleton pregnancies and 201 IU/l in multiple pregnancies (P < 0.0001). Male factor infertility was associated with viable pregnancies (P = 0.004) and tubal factor with non-viable pregnancies (P = 0.003); the lowest HCG level (88 IU/l) was observed in subjects with both male factor infertility and ICSI treatment (P = 0.001). An HCG value of 76 IU/l emerged as the most suitable cut-off point to predict viable pregnancy. Probabilities of each type of outcome related to the HCG level are given.

A single HCG reading on day 12 after embryo transfer helps to plan the subsequent follow-up. Male factor infertility and ICSI are associated with relatively low HCG values in viable pregnancies.