Problems in measuring the effectiveness of infertility therapy.

Couples consulting for infertility are a highly select group, and this makes the evaluation of the effectiveness of a type of therapy difficult. The most obvious selection results from the time they have been unsuccessfully waiting for a conception. Because fecundability is variable from one couple to another, the monthly probability of conceiving after 2 or 3 years of waiting time is low, but the proportion of couples who will conceive within 1 year is still significant and can be predicted. However, in most cases, couples submitted to a specific treatment include hypofertile and totally sterile couples, in unknown proportion. This fact makes difficult the measurement of the effectiveness of therapy, and procedures including control groups should be used. An example of such a process is given.