In-vitro fertilization: how many attempts before success?

Repeated attempts increase the overall rate of success of sterility therapy by in-vitro fertilization. The present study, using data collected between 1983 and 1987 in a Belgian hospital, attempts to investigate the expected number of treatment cycles before success is achieved. The answer requires some knowledge about the degree of independence between success probability and treatment duration. Using mathematical models of implantation, it can be shown that success probability actually decreases during treatment. A method for updating individual probabilities is suggested; it could be used as a prognostic estimation for women undergoing this kind of therapy.