Cumulative Pregnancy Rate

A cumulative pregnancy rate is the share of women in a group who have conceived by a set point in time, such as 12 or 36 months. The denominator is women rather than cycles. Each woman counts once.

That choice is what makes the number honest. Across three published IVF series, nearly 90 percent on average of the women not yet pregnant had stopped by the third cycle, so a per-cycle rate leaves them out.¹ Counting by woman keeps them in. One institute reported on 1,045 patients treated for infertility with NaProTECHNOLOGY. More than 60 percent had conceived by 24 months and nearly 70 percent by 36 months.¹

Ask what sits under the line, and over how long. A conception is not yet a live birth, so the two rates answer different questions.