Background pregnancy rates in an infertile population.

The objective of this cohort study was to determine the true spontaneous background pregnancy rate in an infertile population. A total of 9079 treatment months in infertile couples with infertility of a least 1 year's duration were recorded in a medical school affiliated infertility setting. Results indicated that the spontaneous clinical pregnancy rate in an infertile population was 2. 02% per inactive treatment month, resulting in a cumulative rate after 12 months of 19.9%. It was concluded that couples with a history of infertility have a low but significant background pregnancy rate, which needs to be considered alongside the effectiveness of various treatment modalities.