Fertility Delay Varied by Contraceptive
Method in Study

Heidi Splete

November 13, 2020

Women who used injectable contraceptives had the longest delay in return to normal fertility after discontinuing use, according to a new prospective cohort study.

Women who used hormonal intrauterine devices, copper intrauterine devices, and implants had the shortest delays, based on the same research project, which involved analyzing data from approximately 18,000 women in North America and Denmark.

"Most research on the use of contraceptives and fertility has focused on the effect of oral contraceptives on fecundability," and data on the association between fertility and other contraceptive methods are limited, wrote Jennifer J. Yland, MS, of Boston University School of Public Health and colleagues.

"Given the increasing popularity of long acting reversible contraceptive methods and other alternatives to oral contraceptives, more research into their short- and long-term effects on fertility is needed," the researchers noted.

In the study, which was published in the BMJ, the researchers reviewed data from a total of 17,954 women from three cohort studies of individuals planning pregnancies between 2007 and 2019. Participants reported their contraceptive use and typical menstrual cycle at baseline, then responded to questionnaires every 2 months for up to a year or until pregnancy.

On average, users of injectable contraceptives had the longest delay in return of normal fertility (five to eight menstrual cycles), compared with four cycles for patch contraceptives, three cycles for oral and ring contraceptives, and two cycles for hormonal and copper intrauterine devices and implants.

A total of 10,729 pregnancies were reported within 66,759 menstrual cycles; approximately 77% of the women conceived within 12 months, and 56% conceived within 6 months.

Oral contraceptives were the most common method of contraception (38%), followed by barrier methods (31%), natural methods (15%), and long-acting reversible contraceptives (13%). Intrauterine devices were the most frequently used of long-acting reversible contraceptives (8% hormonal, 4% copper).

The time until fertility returned after discontinuing contraceptives was not associated with duration of contraceptive use.

The study findings were limited by several factors including the potential misclassification of menstrual cycles and the use of self-reports for the time of contraceptive discontinuation, especially for users of injectable contraceptives, the researchers noted.

However, the results were strengthened by the large study size and show "little or no lasting effect" of long-term use of any of the reported contraceptive methods on fertility, the researchers noted. "Understanding the comparative effects of different contraceptives on fecundity is essential for family planning, counseling for contraception, and management of infertility," they said.

Comparison of Contraceptives Can Inform Counseling

The study is important because the use of long-acting reversible contraceptive (LARC) methods (IUDs, implants, patches, and injectable contraceptives) has become increasingly common worldwide, corresponding author Yland said in an interview. "Many women are concerned about the potential effects of contraception on future fertility. However, previous research on this topic has focused mostly on oral contraceptives," she said.

Ms. Yland said that the findings on oral and injectable contraceptives were consistent with previous publications. However, "we were surprised to find that women who had recently used the hormonal IUD had a shorter time to pregnancy, compared with women who used barrier methods," she said.

The take-home message for clinicians is that delays in the return to normal fertility were temporary for all hormonal contraceptive methods, Ms. Yland emphasized. "However, delays in the return of fertility after discontinuing certain hormonal methods, such as injectables, were considerably longer than that shown for oral contraceptives. These findings should be taken into account when women are considering contraceptive choice in the context of family planning and infertility management," she noted.

"Future research should evaluate the potential associations between recent use of hormonal contraceptives and perinatal outcomes," she added.

Managing Expectations Helps Patients Plan

"The question of return to fertility is one that many patients who use contraception have unless they have completed their child bearing," said Sarah W. Prager, MD, of the University of Washington, Seattle, in an interview. "For patients who want to plan a pregnancy, knowing what to expect in terms of return to fertility is important so they can make sure they are in the space and place they want to be with their health, life, job, and partner," she said.

Prager said she was not surprised by the study findings because they agree with previously published data. "Overall, except for the injection, people using any form of contraception are back to their baseline fertility within a few months," she noted. "It also makes perfect sense for return to fertility to be longer with the injection, as it is designed to prevent pregnancy for 16 weeks after the injection is given. Unlike all the other methods, it cannot be removed from the body once given," she said.

"Clinicians should continue to advise patients that their return to baseline fertility is relatively rapid with any contraception other than the Depo-Provera injection," said Prager. "There are no data to support a benefit in switching from an IUD or implant to a combination hormonal method (pills, patch, ring) before starting to try to conceive," she said.

"This study tries to account for differences in baseline fertility for people using the different methods, but since the choice of method was not randomized, there could still be baseline differences that were not measured or accounted for," Prager noted. "A randomized study would certainly eliminate some of these biases; however, I don't think the differences found in this study are so profound as to require such study," she said. "Generally speaking, almost 80% of people using any form of contraception were able to conceive within 1 year of trying, which has been the stated fertility data for decades," she said.

The study was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health. Lead author Ms. Yland had no financial conflicts to disclose. Prager had no financial conflicts to disclose.

SOURCE: Yland JJ et al. BMJ. 2020 Nov 12. doi: 10.1136/bmj.m3966.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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