Estimation of fertility and fecundity in women receiving artificial insemination by donor semen and in normal fertile women.

The pregnancy rates after artificial insemination by donor semen (AID) have been compared with pregnancy rates in normal fertile women to assess the efficiency of AID. To do this, the curve y = a(1-(1-b)x) was fitted to life-tabled cumulative pregnancy rates. The equation describes a model in which the parameter a is the proportion of women who are potentially fertile under the conditions of treatment, and in which the parameter b is the pregnancy rate per cycle (or fecundity) of these fertile women. For 259 AID patients with no previous pregnancy a was 65% while for 57 AID patients with a previous pregnancy after AID 'a' was 99.9%. The values of b were similar for the two groups of patients, being 20% and 22% respectively. Women without fertility problems who had become pregnant after discontinuing oral contraception provided the reference group. Since only pregnant women were selected, a was 100% by definition. The values of b for the reference group were 22% for 100 primigravid women and 20% for 100 multigravid women. Only 65% of the AID patients were potentially fertile with AID, but those that were fertile became pregnant at the same rate as normal women who discontinued oral contraception.