Early pregnancy wastage following late implantation of embryos after in-vitro fertilization and embryo transfer.

Serial plasma concentrations of human chorionic gonadotrophin (HCG), progesterone and oestradiol were measured in pregnancies after in-vitro fertilization and embryo transfer. The first detection day of HCG after embryo transfer (8.4 +/- 1.1) and the HCG doubling time (DT) of 64 normal singleton pregnancies were compared to those of 14 first-trimester miscarriages. The same parameters were evaluated in nine late-implanted conceptions, seven of which resulted in early pregnancy wastage. The HCG DT of late-implanted pregnancies was consistent with that of singleton term pregnancies in the first 12 days, while first-trimester miscarriages which had implanted at the usual time had a significantly longer DT from implantation onwards. The reduced trophoblastic secretory rate suggests poor embryo quality in these cases. A decreased progesterone/oestradiol ratio was observed in late-implanted pregnancies but because of the small number of individuals, no definite conclusion can be drawn. More patients with delayed implantation should be tested to justify this observation.