Human chorionic gonadotropin patterns in early pregnancy after assisted reproduction

Assisted reproduction implies increased risks of pathological pregnancy, necessitating close follow up of early pregnancy. The use of serum hCG levels two and three weeks after embryo transfer for prediction of pregnancy outcome after in vitro fertilization-embryo transfer (IVF/ET) or gamete intrafallopian transfer (GIFT) was evaluated.

Three hundred and twenty-nine treatment cycles were included. Serum samples were obtained on days 14 and 21 after ET and hCG was determined by fluoroimmunoassay. Receiver operating characteristic (ROC) curves were analyzed to find cut-off levels of hCG giving maximal sensitivity and specificity, identifying a low risk group and a high risk group with regard to pathological pregnancy.

The group of patients carrying a viable pregnancy had significantly higher hCG levels two and three weeks after ET than the group of patients carrying a pathological pregnancy. Furthermore, the daily increase in hCG was higher. In multiple gestations, the levels of hCG were significantly higher compared to singleton pregnancies. Ninety per cent of the patients with an hCG level > or = 150 IU/L 13-15 days after ET carried a pregnancy to term (the low risk group). Conversely, 50% of the patients with hCG < 150 IU/L carried a pathological pregnancy (the high risk group).

A single determination of the hCG level two weeks after ET, combined with transvaginal ultrasound two to three weeks later, is a reliable follow-up. In cases of subnormal hCG levels (< 150 IU/L), a second hCG determination one week later followed by sonography is recommended.