Duration of involuntary infertility and subsequent pregnancy

During 1978-1983, 1,040 couples had been evaluated at our infertility clinic and subsequently followed up for an average of two years. The length of time the couple had been trying for a pregnancy (trying time) is shown to be strongly related to the subsequent chances of pregnancy. There are few effective treatments for male infertility and, therefore, these data may represent the spontaneous fertility rates from an untreated population. This background pregnancy rate should be useful to any physician planning a trial of treatment for the infertile couple when pregnancy is the success criterion, and allowance needs to be made for this spontaneous pregnancy rate when analyzing the results of treatments. Review of the literature suggests that some reported results could be misleading because of failure to allow for this background pregnancy rate.