Current status of in-vitro fertilisation and implantation of human embryos.

Between October, 1980, and April, 1983, embryos fertilised in vitro were replaced in the uteri of 1200 women. The "clinical" pregnancy rate rose from 16.5% from October, 1980, until September, 1982, to almost 30% in 1983. The proportion of pregnancies ending in abortion varied from 25-35%. Factors favourably modifying implantation rate were maternal age of under 40 years, priming with clomiphene alone, and the replacing of more than one embryo in the uterus. The replacing of two or more embryos, increasing maternal age, a poor obstetric history, and high levels of follicular oestrogens raised the chances of abortion.