Injectable contraceptives associated with longest delayed fertility return
After adjusting for personal factors, medical history, lifestyle characteristics, and indicators of underlying fertility, the authors found that injectable contraceptive use was associated with decreased fecundability compared with barrier method use (fecundability ratio [FR], 0.65; 95% confidence interval [CI], 0.47–0.89). Hormonal IUD use was associated with slight increases in fecundability compared with barrier method use (FR, 1.14; 95% CI, 1.07–1.22) and copper IUD use (FR, 1.18; 95% CI, 1.05–1.33). All other contraceptive methods were not significantly different from barrier methods.
LARC method use was associated with the shortest delay in return of normal fertility (2 cycles), followed by oral and ring contraceptives (3 cycles) and patch (4 cycles). Women using injectable contraceptives experienced the longest delay (5–8 menstrual cycles). Lifetime duration of contraceptive use did not impact fecundability in the North American cohort.
Study strengths and limitations
This large, prospective study contributes useful information about fecundability after stopping contraceptive methods. It confirms earlier studies’ findings that showed decreased fecundability after stopping injectable contraceptives. Study participants’ most recent method used was similar to overall US method distribution.1
Study limitations include online recruitment of self-selecting participants, which introduces selection bias. The study population was overwhelmingly white (92%) and highly educated (70% with college degrees), quite different from the US population. These findings may therefore have limited generalizability. Additionally, injectable contraceptive users had higher body mass index and were more likely to smoke and have diabetes, infertility, or irregular menstrual cycles. IUD users were more likely to be parous and have a history of unplanned pregnancy, indicating possible higher baseline fertility. Even after adjusting, possible unmeasured factors could impact study results. ●
WHAT THIS EVIDENCE MEANS FOR PRACTICE
This is the largest study to date to evaluate fecundability after stopping different contraceptive methods among women planning pregnancies. The study confirms previous research that associated injectable contraceptives with delayed return of normal fertility. It provides reassurance for counseling users of IUDs, implants, oral contraception, ring, and patch: those methods were not associated with reduced fecundability compared with barrier methods. The study also suggests long-term contraceptive use does not decrease fecundability.
Women may ask when to stop their contraceptive method to optimally time a pregnancy. In this study, measurements of return to normal fertility were imprecise. Individualized counseling, accounting for personal circumstances, is still best when advising when to stop contraception for couples planning pregnancy.
LISA HOFLER, MD, MPH, MBA, AND LINDSAY DALE, MD