Return of fertility in women discontinuing injectable contraceptives

2 recent studies largely dispel concern about the restoration of fertility after discontinuation of injectable contraceptives. After cessation of use of depot medroxyprogesterone acetate (DMPA) or norethisterone enanthate there is some delay in fertility restoration, but fertility is not impaired once the progestogen is cleared from the body. Pharmacokinetic data suggest that norethisterone enanthate exerts less of an inhibitory effect on the hypothalamic-pituitary-ovarian system than DMPA, so that ovulation returns earlier after discontinuation of the former injectable. There appears to be no significant difference between nulligravid and parous women in the return of fertility, indicating that use of injectable contraceptives does not need to be restricted to women who have completed their families. In Pardthaisong's study of over 1000 Thai women, the median delay until conception after contraceptive discontinuation was 3 months among oral contraceptive users, 4.5 months for the IUD, and 5.5 months for DMPA users. 36 months after discontinuation, only 6.4% of the 796 DMPA former users surveyed had failed to conceive. In a smaller scale study by Fotherby et al, the conception rate among discontinuers of norethisterone enanthate did not differ significantly from that among nonusers of contraception or users of nonsteroidal methods once an 8-week period for the clearance of norethisterone from the body had elapsed. The mean time to ovulation is similar to the clearance for norethisterone; for DMPA, in contrast, the mean time to ovulation is considerably longer than that of the clearance. In discontinuers of DMPA, the mean time for the return of ovulation (210 days) is only slightly less than the mean time for the return of fertility (260 days). However, for norethisterone enanthate, the mean time to conception is about 170 days compared to just over 80 days for the return of ovulation.