Janelle asked
Do birth control pills affect fertility in women?
Answer
It's certainly natural to wonder whether or not birth control pills, that primarily prevent pregnancy by inhibiting ovulation, will have long term effects that could impact their ability to become pregnant in the future. Many people believe that oral contraceptives have long lasting, negative effects on fertility and take steps to mitigate that risk. One prevailing thought is that it is necessary to take periodic breaks from birth control pills to allow the body to 'return' to a natural state, although this is not an evidence based approach.
As always when answering questions like this, there isn't a definitive answer on the subject but there certainly is a generally accepted medical consensus which is that oral contraceptive use does NOT negatively impact fertility in woman. The majority of data shows that normal fertility will resume almost immediately after stopping oral hormonal contraceptives pills, regardless of how long they were being used.
In fact, much of the data on the subject shows that women who attempt to get pregnant AFTER stopping birth control not only succeed just as quickly as women who have not taken oral contraceptives, but actually find it easier to conceive. There could be a variety of explanations or reasons for this including the fact that hormonal contraception can mitigate many factors that prevent successful pregnancy such as pelvic inflammatory disease, ectopic pregnancy and certain forms of cancer.
One of the more comprehensive studies on this matter is the EURAS-OC (European Active Surveillance Study on Oral Contraceptives). The study followed women for a 2 year period after stopping oral contraceptives and observed pregnancy rates compared with those who had not taken oral contraceptives. The results showed there was no statistically significant difference in pregnancy rates between the two groups. The oral contraceptive group, who averaged 7 years of use, when trying to conceive, had pregnancy rates of 21% one month after discontinuation and 79% one year after discontinuation. The non-oral contraceptive group, when trying to conceive, had pregnancy rates of 20% after one month and 80%.
While data from a variety of studies show that oral contraceptive use does not inhibit pregnancy rates versus non-users, it would be irresponsible to completely discount anecdotal evidence of personal stories from individuals who have had trouble conceiving after stopping birth control pills. It is important to be empathetic and try to discern the reasons that are making conception a challenge. There could certainly be unknown effects that we just don't know about yet, which makes it important to continue gain as much information as we can.
Aside from some sort of potential negative effects we just aren't aware of, we do have some insight on why some people may have difficulty conceiving once stopping the medication. Fertility depends on many factors that are unrelated to contraceptive use. Most often, a delay in conception is likely related to older age or an underlying ovulation problem. If there was an underlying or preexisting ovulation problem that was being treated with oral contraceptives, discontinuing that therapy often unmasks the original problem, which of course makes it more difficult to conceive. In these cases, many times it is necessary to use fertility medications to produce predictable ovulation.
It is important to note that the above information is in regards to ORAL contraceptive pills. Ovulation and this fertility can be delayed in women that get the injectable depot medroxyprogesterone contraception (Depo-Provera). This form of contraception is for those who do not intend to have kids in the near future as it can take anywhere from 2 months to over a year to completely clear the hormones from the body. On average, it takes about 10 months after the last injection to become pregnant if trying to conceive.
In addition to the EURAS-OC study we cited and discussed above, we wanted to provide some additional excerpts from research studies on this subject. Below we have singled out some articles and their written conclusions.
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Fertility after discontinuation of treatment with an oral contraceptive containing 30 mcg of ethinyl estradiol and 2 mg of dienogest
Wiegratz I, Mittmann K, Dietrich H, et al. . Fertil Steril 2006;85:1812-9.
Conclusion: "The present prospective study revealed only a slight delay in regaining fertility during the first three cycles after cessation of EE/DNG. Thereafter, the cumulative rate of conception did not differ from that observed in fertile women who attempted to become pregnant without prior contraception."
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Prolonged use of oral contraception before a planned pregnancy is associated with a decreased risk of delayed conception.
Farrow A, Hull MG, Northstone K, et al. Hum Reprod 2002;17:2754-61.
Conclusion:"Women who have prolonged use of oral contraceptives might be reassured that they will not be disadvantaged in terms of time taken to achieve conception."
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Rate of pregnancy after using drospirenone and other progestin-containing oral contraceptives.
Cronin M1, Schellschmidt I, Dinger J. Obstet Gynecol. 2009 Sep;114(3):616-22.
Conclusion:"Previous oral-contraceptive use does not negatively affect initial and 1-year rates of pregnancy after oral-contraceptive cessation. A comparison of these data with data external to this study indicates that the negative effect of aging on fecundity is not amplified by oral-contraceptive use."
