Women who stop using some forms of contraception may have to wait up to eight months before their fertility returns, suggests research published online in The BMJ.
US and Danish researchers measured the delay in return of fertility in women after use of a variety of contraceptive methods.
They found that the time until fertility returned varied depending on which method was used. The return to fertility did not depend on how long the woman had been using contraceptives.
Globally, about 22% of reproductive-aged women used hormonal contraception in 2019.
Male condoms and oral contraceptives are the most commonly used methods in North America and Europe, but long-acting reversible contraceptive (LARC) methods such as intrauterine devices (IUDs), implants, patches and injectable contraceptives have become increasingly popular globally.
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, 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, a team of Boston University School of Public Health researchers led by Jennifer Yland, in collaboration with Aarhus University in Denmark, set out to evaluate the association between pre-pregnancy use of a variety of contraceptive methods and the subsequent probability of becoming pregnant (fecundability).
For their study, the researchers pooled data from three studies that altogether involved nearly 18,000 women from Denmark and North America who planned pregnancies between 2007 and 2019.
At the start of the study, the women reported their contraceptive histories, as well as personal, medical, and lifestyle information.
Follow-up questionnaires were sent every two months for up to 12 months or until they reported they had become pregnant. More than 80% of participants completed at least one follow-up questionnaire.
Overall, there were 10,729 pregnancies recorded in these women during 66,759 menstrual cycles of observation. Approximately 56% of women conceived within 6 cycles of follow-up, and 77% within 12 cycles.
The most commonly reported method of contraception was oral contraceptives (38%), followed by barrier methods such as condoms, diaphragm and sponge (31%), and natural methods such as withdrawal, and avoiding sex when fertile (15%).
Approximately 13% of women used long-acting reversible contraceptive methods; the most frequently used of these were IUDs—8% of women used the hormonal IUD and 4% of women used the copper IUD as their last method of contraception.
Women 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.
Women who used injectable contraceptives had the longest delay in return of normal fertility (five to eight cycles), followed by users of patch contraceptives (four cycles), users of oral contraceptives and vaginal rings (three cycles), and users of hormonal and copper intrauterine devices and implant contraceptives (two cycles).
The study had important limitations. The authors did not have data on the date of the last injection for women who used injectable contraceptives, and instead relied upon self-reported time since discontinuation of contraception for all methods studied.
Nevertheless, the results indicate that return of normal fertility varies substantially by contraceptive method.
The authors noted that: “Our results, although imprecise, indicate little or no lasting effect of long term use of these methods on fecundability …. these findings might inform clinical recommendations on contraceptive decision making.”
Wide ranges of effective and safe reversible modern contraceptives are available in the contemporary world. Despite the advancement in contraceptive technologies and organized international effort over the last few decades; the concern of women who use reversible contraception related to time to return of fertility still remained unanswered [1–3].
Most contraceptives have been modified to improve their safety and tolerability without compromising efficacy. It is also important to know the effect of contraception use on the subsequent fertility [1, 3].
However, currently evidences regarding resumption of pregnancy after contraceptive discontinuation are inconclusive. Delay of fertility after termination of contraception remains a big concern for women who are using contraception. Particularly women who ever experienced post pill amenorrhea or fail to become pregnant within expected date of fertility after termination of contraception have speculated contraceptive options cause delayed return of fertility.
Controlling unwanted fertility with highly effective reversible contraception allowed couples to have the number of children they want at the time they want to have. On the other hand fertility delay or impairment as a result of prior contraception use may lead to dissatisfaction and lower contraception use irrespective of actual desire [3–7].
Approximately 15% of couples experience infertility (fail to get pregnant within 1 year) , women who use hormonal contraception have considerable concern of delayed or impaired fertility upon discontinuation. Delayed return of fertility or infertility among previous contraceptive users is commonly linked to their contraceptive use.
Therefore, this premise that leads to misconception among family planning users need to be synthesized and tested using the available evidences across the globe.
These concerns were also raised by scholars from early reports that Oral Contraceptive use may cause secondary amenorrhea, which is associated with anovulation and reduced reproductive fecundity. IUD may also cause infertility secondary to pelvic inflammatory disease (PID) .
It was believed that exogenous hormonal therapy causes delayed return of normal function of hypothalamic/pituitary/ovarian axis [8–11] and temporary infertility . However these concerns were disproved from more recent studies partly from development of low dose hormonal contraception, prevention of PID and implementation of scientific technique [13–16].
There are a number of studies and few specific reviews conducted to assess the effect of different forms of contraceptives on subsequent pregnancies. The findings were inconclusive, in some studies contraception shown to have only an initial (temporary) delay in conception for the first few months after discontinuation [13–16].
While in recent studies no association was observed between contraceptive use and secondary amenorrhea [17–19] except with higher doses of oestrogen . On the other hand many studies have reported that, the type of intrauterine device as well as duration of use has not been found to be related to fertility return .
Therefore, we aimed to conduct a comprehensive systematic review and meta-analysis through reviewing globally published observational studies on the effect of fertility return after discontinuation of different contraception among married and in union. Return of fertility is measured in terms of pooled rate of fertility return within 1 year in order to bring conclusive evidence. So that policy makers and other stakeholder could have synthesized evidence to rely on in decision making on prospect of the problem.
According to this review 83.1% (95% CI = 78.2-88%) of women who discontinued contraception became pregnant within the first 12 months. Return of fertility at the first year was not significantly different for hormonal methods and IUD users. Similarly type of progesterone in contraception and duration of oral-contraceptive use do not significantly influence return of fertility following cessation of contraception. However effect of parity in resumption of pregnancy following cessation of contraception was inconclusive.
The rate of fertility return in this review was comparable to other reports of reviews and articles which assessed specific types of contraception [45–48]. The rate of pregnancy for oral contraceptives, copper IUDs and the LNG-IUS ex-users was also overlap with each other and comparable to previous findings.
However the finding was slightly lower than reports of women who discontinued barrier methods or using no contraceptive method of 85.2– 94% [49, 50]. This difference may be due to the fact that hormonal contraceptives commonly take months to clear from the body which results in temporary delay in resumption of pregnancy for months [44, 47, 48].
One year pregnancy rate of (37.5-90%) following cessation of Implant also overlaps across different studies [45, 46]. There are studies which report exceptionally low rate of pregnancy within 1 year after cessation of contraception as evidenced by Affandi et al.  which reports (37.5 and 48.8% for Norplant and Implanon ex-users respectively).
However when the study with low rate of pregnancy after cessation of contraception is removed the rate of fertility return is comparable to other methods. Moreover, no significant difference was reported between different forms of Implants. This may be explained by the fact that implants are impregnated with similar hormone which doesn’t create a difference.
Return of fertility following termination of IUD was not compromised at all and resumption ranges between (71-96%) with a mean of 84.75%. Moreover, type of IUD and duration of use as well as addition of hormones to the device do not compromise pregnancy [37–43]. In line with this finding Mansour et al.  reported pregnancy rate of 86.1 to 92.3% following termination of IUD which is comparable to natural method users and non-users.
This finding also witnesses that prompt resumption of fertility after termination of IUD. As explained by other findings type and duration of IUD use doesn’t matter the rate of pregnancy after cessation [46, 47].
It is commonly believed that oral contraception may compromise conception, however, this review reported higher rate of conception (87%). In line with this finding other researchers reported comparable return of fertility after cessation of oral contraception [47–50]
However, this review and meta-analysis appreciate presence of brief delay in return of fertility after cessation of hormonal contraception use until the bioavailability of the hormone in blood is completely cleared. It is also noted that the 3 months hormonal contraception use hinders pregnancy, but the effect is extremely low for12 month users and no effect for 24 month users [32–36, 47–49].
The Concern of impaired fertility which was reported with high-dose of oral contraceptive pills in early years is not a problem currently. This is due to presence of low dose contraception regimen for use [33, 34, 48].
Our review also shows that the duration of contraception use was not significantly affected with return of fertility. It is in line to many studies included in the review [24–44] and the report of some other researches [45–49]. On the other hand there are evidences which narrate women who used oral contraceptives for a longer duration may had a slightly lower rate of pregnancy than did women using oral contraceptives for a shorter period of time  which could be the effect of age, in which fertility decreases as age advances.
However, since none of the studies were randomized control trials and most of the studies had small sample sizes, the possible relationship between extended use of hormonal contraception and the rate of resumption of pregnancy may not come across through appropriate and reliable conclusion.
Similarly our review showed that the progestin type had no major effect on the rate of pregnancy over the short term and long-term. This is because rather than duration, dose matters. However currently only low dose preparations are in use.
Therefore, delay in fertility may not be common following termination of contraception use. In addition, return of fertility among women discontinuing extended or continuous OC regimens is similar to that observed with cyclic OCs [32–36]. This result was also reported from previous reviews assessing the return of fertility following cessation of oral contraception [45–50].
The effect of parity on the rate of fertility was inconclusive. The finding of this review shows that parity may or may not enhance fertility. Studies included in the review particularly compared nulliparous and multiparous women which ignored the rate of infertility . Therefore, higher rate of pregnancy among multiparous women who are proved to be fertile are expected. In all cases baseline prevalence of infertility may influence fertility rates of women seeking pregnancy following discontinuation of a contraceptive method.
reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6055351/
More information: Jennifer J Yland et al, Pregravid contraceptive use and fecundability: prospective cohort study, BMJ (2020). DOI: 10.1136/bmj.m3966