Human chorionic gonadotrophin measurements in the luteal phase of the menstrual cycle of infertile and fertile women.

Serum human chorionic gonadotrophin (HCG) determinations were performed every other day during the luteal phase of the menstrual cycle of 20 women suffering from unexplained infertility and of 20 women assumed to be fertile. HCG was determined by a specific radioimmunoassay which applied an antiserum directed against the HCG-beta subunit. The group of infertile patients demonstrated detectable serum HCG in only three cases. No clinically confirmed pregnancies were achieved in this group. Eighteen of the 20 women presumed to be fertile showed detectable HCG levels. Five of these achieved ongoing pregnancies, while 13 women revealed increased HCG levels without delayed menstrual periods. The first day of detection of HCG during the luteal phase did not differ between the two groups. In the five women with ongoing pregnancies the time of detection of HCG ranged from day 5 until day 12 after ovulation. It is concluded that the high rate of increased HCG values in the fertile group may represent early conceptual loss, but the apparently disorderly HCG results indicate the need for cautious interpretation of HCG determinations during the luteal phase. Furthermore, early conceptual loss forms no major explanation for unexplained infertility.