Predictive value of plasma human chorionic gonadotropin measured 14 days after Day-2 single embryo transfer

Introduction: Prediction of pregnancy outcome after in vitro fertilization is important for patients and clinicians. Early plasma human chorionic gonadotropin (p-hCG) levels are the best known predictor of pregnancy outcome, but no studies have been restricted to single embryo transfer (SET) of Day-2 embryos. The aim of the present study was to investigate the predictive value of p-hCG measured exactly 14 days after the most commonly used Day-2 SET on pregnancy, delivery, and perinatal outcome.

Material and methods: A retrospective analysis of prospectively collected data on 466 women who had p-hCG measured exactly 14 days after Day-2 SET during a randomized trial including 1050 unselected women (aged 18-40 years) undergoing their first in vitro fertilization/ intracytoplasmic sperm injection treatment.

Results: The p-hCG predicted clinical pregnancy [area under the curve (AUC) 0.953; 95% CI 0.915-0.992] significantly better than ongoing pregnancy (AUC 0.803, 95% CI 0.717-0.890) and delivery (AUC 0.772, 95% CI 0.691-0.854). Women with p-hCG levels in the lowest quartile had significantly lower clinical pregnancy, ongoing pregnancy, and delivery rates (p < 0.001), whereas the pregnancy outcome and post-clinical pregnancy loss remained similar throughout the three highest p-hCG quartiles. The p-hCG level was related to neither birthweight nor gestational age at delivery.

Conclusions: Clinical pregnancy is significantly better predicted by p-hCG compared with ongoing pregnancy and delivery. Clinical pregnancy rates, ongoing pregnancy rates, and delivery rates remained similar throughout the three highest p-hCG quartiles with no trend towards "the higher the better".