A model to show human uterine receptivity and embryo viability following ovarian stimulation for in vitro fertilization.

A comparison of the implantation rates following in vitro fertilization (IVF) and embryo transfer (ET) for four major groups indicates differences in the implantation rates as well as in the incidence of multiple implantation. By assuming that the probability of implantation is the product of two variables, uterine receptivity (U) and embryo viability (E), estimates for U and E are derived for each of the four IVF groups using maximum likelihood methods. The UE model is tested using chi-squared goodness-of-fit methods for predicted implantation rates versus observed. The possibility that differences in U values between groups are due to different ovarian stimulation protocols is discussed, as is the value of the UE model in highlighting differences between IVF groups and its importance in predicting multiple pregnancy rates.