Highly specific and sensitive rise in days 14-17 pro-αC inhibin with clinical pregnancy after frozen embryo transfer with ovulatory cycles

Abstract

Background: Pro-αC inhibins are luteal derived analytes peaking in the maternal serum as early as Day 16 after conception. We set out to verify a previous post hoc analysis which suggested that pro-αC levels measured this early are extremely sensitive in predicting clinical pregnancy success after unstimulated IVF with ovulatory cycles. Methods: Prospective observational study of 246 women undergoing frozenembryo transfer with ovulatory cycles. Serum pro-αC and β-HCG levels at 14-17 days after conception were measured by enzyme-linked immunosorbent assay and grouped according to whether a clinical pregnancy occurred (demonstrable cardiac activity at ≥6 weeks' gestation). Results: Of 34 (13.8%) women who achieved a clinical pregnancy, median (25th-75th centile) Days 14-17 pro-αC levels were 995 pg/ml (758-1463), 6- to 7-fold higher than levels observed in the remainder who did not fall pregnant (112.8 pg/ml (104-121); P < 0.0001). At a fixed 95% specificity, pro-αC was 100% sensitive in predicting clinical pregnancy. The best specificities achieved at 100% sensitivity were; 94.8% for pro-αC, 96.7% for β-HCG and 98.1% when both analytes were combined. Conclusions: Clinical pregnancy is always associated with a release of luteal derived pro-αC 14-17 days after conception. Pro-αC may play a possible biological role and be a useful clinical biomarker of luteal health. © The Author 2007. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.