Return of fertility in women discontinuing injectable contraceptives.
Level 5 - mechanism / opinion, no new human data
Narrative review summarizing findings from two previously published observational studies
PubMed 12315276 · doi:10.3109/01443618609081724
What was done
This review summarizes data from two studies (a study of over 1,000 Thai women by Pardthaisong and a smaller study by Fotherby et al.) evaluating the return of ovulation and conception after discontinuing injectable progestogen contraceptives—depot medroxyprogesterone acetate (DMPA) and norethisterone enanthate—in comparison to oral contraceptives, intrauterine devices (IUDs), nonsteroidal methods, or non-use.
What was found
In the Pardthaisong cohort, median delay to conception was 3 months for oral contraceptives, 4.5 months for IUDs, and 5.5 months for DMPA. At 36 months post-discontinuation, 6.4% of 796 DMPA users had not conceived. For DMPA, mean time to return of ovulation was 210 days and mean time to conception was 260 days. For norethisterone enanthate, mean time to ovulation was just over 80 days and mean time to conception was approximately 170 days; conception rates did not differ significantly from non-users after an 8-week clearance window. Return of fertility did not differ significantly between nulligravid and parous women.
Why it matters
These findings demonstrate that injectable contraceptives cause a temporary, pharmacokinetically driven delay in conception rather than permanent infertility, supporting their safety for women regardless of prior parity.
Limits
The report is a narrative summary rather than primary research or a systematic review. The abstract omits sample size, confidence intervals, and loss to follow-up details for the norethisterone enanthate cohort. Important confounders affecting conception rates, such as partner fertility, age distribution, and intercourse frequency, are not reported in the abstract.
Cited by
- supports A single intramuscular injection of Depo-Provera can prevent ovulation for up to 18 months.