Delayed appearance of plasmatic chorionic gonadotropin in pregnancies after in vitro fertilization and embryo transfer.

The detection of pregnancy through the rise of human chorionic gonadotropin hormone secretion, on maternal plasma level, has been studied in normally developed pregnancies following in vitro fertilization and embryo transfer (IVF-ET), and compared with two other groups of pregnancies, the first group being pregnancies following artificial insemination with donor semen (AID) in spontaneous cycles ("AID group") and the second group being pregnancies following in vivo fertilization in a stimulated cycle ("stimulated group"). The day of human chorionic gonadotropin detection level significant for pregnancy (Dd) has been first defined and then determined for each pregnancy. Thereafter, mean levels for Dd (Dd) have been compared for each pregnancy group. It has been found that in pregnancies following IVF-ET, Dd is 12.05 +/- 0.8 days after ovulatory stimulus, which is delayed in comparison with spontaneous cycle pregnancies (Dd = 9.5 +/- 1.0) and with stimulated cycle pregnancies (Dd = 8.0 +/- 1.5). The hypothesis to explain this observation is then discussed.