Long-acting reversible contraceptives such as intrauterine devices (IUDs) and injectables are on the rise, spurred perhaps in part by the political climate around reproductive rights. But when someone decides to stop using one of these contraception strategies to have a baby, there is little data on how long it will take for fertility to return.
Now, a School of Public Health study evaluates the delay in fertility after using most forms of contraception, showing a wide range in how long the effects of different contraceptives linger.
Published in The BMJ, the study found that women who used injectable contraceptives had the longest delay in return of normal fertility (five to eight menstrual cycles), followed by users of patch contraceptives (four cycles), users of oral contraceptives and vaginal rings (three cycles), and users of hormonal and copper IUDs and implant contraceptives (two cycles). How long women had used one of these methods did not have an effect on how long it took for fertility to return.
“For all hormonal contraceptive methods, delays in the return to normal fertility were short-term. However, the contraceptive action of certain methods, such as injectables, may temporarily persist after discontinuing contraception,” says study lead author Jennifer Yland, a doctoral student in epidemiology.
“These findings should be taken into account when women are considering their contraceptive options in the context of family planning or infertility management,” she says.
Previous studies on the return to fertility after use of long-acting reversible contraceptives have been small and inconsistent, leaving many questions unanswered. Earlier research has focused mainly on the effects of oral contraceptives (“the pill”), with most studies showing short delays of approximately three months in the return of fertility after women stopped taking them.
To round out the picture, Yland and colleagues at SPH and at Aarhus University in Denmark evaluated the association between pre-pregnancy use of different contraceptive methods and the subsequent probability of becoming pregnant.
They pooled data from nearly 18,000 women who participated in three studies—Snart Gravid and Snart Foraeldre in Denmark, and the SPH-based Pregnancy Study Online (PRESTO) in the US and Canada—when they were planning pregnancies between 2007 and 2019. When joining each of these studies, the women reported their contraceptive histories, as well as personal, medical, and lifestyle information, and they then answered follow-up questionnaires every two months for up to 12 months or until they reported they had become pregnant.
Overall, there were 10,729 pregnancies recorded in these women during 66,759 menstrual cycles of observation. Approximately 56 percent of women conceived within six cycles of follow-up, and 77 percent within 12 cycles.
The most commonly reported method of contraception was oral contraceptives (38 percent), followed by barrier methods such as condoms, diaphragm and sponge (31 percent), and natural methods such as withdrawal, and avoiding sex when fertile (15 percent). Approximately 13 percent of women used long-acting reversible contraceptive methods, with IUDs being the most common—8 percent used the hormonal IUD and 4 percent used the copper IUD as their last method of contraception.
The participants experienced short-term delays in a return to fertility if they had recently stopped using oral contraceptives, the contraceptive ring, and some long-acting reversible contraceptive methods (compared with users of barrier methods).
The study’s senior author is Lauren Wise, professor of epidemiology. The other co-authors are: Kathryn Bresnick, a doctoral student in epidemiology; Elizabeth Hatch and Kenneth Rothman, professors of epidemiology; Amelia Wesselink, postdoctoral associate in epidemiology; Henrik T. Sørensen, chair of the Department of Clinical Epidemiology at Aarhus University Hospital in Denmark and adjunct professor of epidemiology at SPH; Ellen M. Mikkelsen, associate professor of epidemiology at Aarhus; and Krista F. Huybrechts, associate professor of medicine at Harvard Medical School.