Mechanisms and factors of early pregnancy wastage in in vitro fertilization-embryo transfer patients.

Although the pregnancy rate per transfer of the Norfolk In Vitro Fertilization-Embryo Transfer (IVF-ET) program has been reported as between 25% and 35%, the viable pregnancy rate per transfer is only 15% to 20%. An understanding of the mechanism(s) and etiologic factors of miscarriage among IVF patients might suggest changes that could prevent some early pregnancy wastage. Forty-seven consecutive single pregnancies and 26 miscarriages (October 1985 to November 1986) were included in this study. Factors such as implantation time, date of corpus luteum rescue (CLR), embryo quality, and corpus luteum activity after rescue were studied and compared between term pregnancy and miscarriage groups. Results are discussed in detail in this paper.