Return of ovulation after abortion and after discontinuation of oral contraceptives.

The return of ovulation after abortion and discontinuation of oral contraceptives was determined by plasma progesterone measurements. Plasma samples were obtained from 67 women at 3 to 6 weeks after abortion and in two groups of postabortion women at 3 to 6 weeks after cessation of oral contraceptives. In the first of these latter two groups, 50 women started taking the pills (containing 30 microgram of ethinylestradiol and 150 microgram of levonorgestrel) immediately after abortion, and the second group of 29 women started taking the pills from the first postabortion menses. Ovulation had recurred in 34% of the women 3 weeks after abortion and in 78% of the women at 6 weeks. The return of ovulation had occured in approximately 55% at 3 weeks after cessation of oral contraceptives in both groups. At 6 weeks after cessation, approximately 85% of women had ovulated in both groups. Luteal function in these two groups was found to be equal and was significantly better in both groups than during the first postabortion cycle (P < 0.005). It is concluded that the early return of ovulation after abortion makes it necessary to commence effective contraception immediately after abortion. The immediate administration of oral contraceptives after abortion does not affect the return of ovulation after discontinuation of oral contraceptives.