How Long Does It Take For Birth Control To "Leave Your System" ?

Photographed by Megan Madden.
After finding out that her boyfriend wants "five or six" kids, Khloe Kardashian met with a fertility specialist on this week's Keeping Up With The Kardashians. But she was told that she had fewer eggs than expected for a woman her age. In order to get a better idea of her fertility level — and, of course, to actually get pregnant — Khloe needed to go off her birth control pills. So, now comes the big question: How long does it take after stopping hormonal birth control to become "fertile" again?
If you're on the pill, not very long. "Birth control pills are a very short-acting medication, meaning that you have to take one pill every single day," explains Shefali Mavani Shastri, MD, an Ob/Gyn at Reproductive Medicine Associates of New Jersey. So, the medication itself "leaves your system" within a day. (If you've ever missed a pill and started spotting, that's why!)
Most patients who have been on the pill find themselves back in their normal cycle within a month after their last dose, Dr. Shastri says. But if you've been on the pill for more than six months, or you're taking a higher-dose form of the pill, it might take you a few more cycles for things to even out and return to your baseline.
For your birth control to be effective, the pill needs to suppress your ovulation. And, as Khloe found out, that might make your initial fertility assessment (if you get one) a little confusing. Why? Well, your follicles, which house your eggs, are held within your ovaries, Dr. Shastri says. You have some eggs held "in reserve" in the follicle in a dormant state: some actively making their way down the pipeline for the next few months, and some that are actually "recruited" to begin maturing every month (only one of those typically makes it to your fallopian tubes).
However, doctors can only see those eggs that have been recruited on an ultrasound, and they use that number as one marker of a person's overall fertility. "If a woman is coming off birth control and she is suppressed, you may not see as many eggs on the ultrasound," Dr. Shastri explains. "But if you wait a month, or just a couple of weeks, you might see a more accurate assessment of her reserve."
However, that's just for the pill. Other types of hormonal birth control affect us differently, depending on the dose of hormones, where they're delivered in the body, and how long they act within the body. The hormonal IUD, for instance, provides hormones delivered directly to the ovaries that are meant to be longer-lasting than the pill. After getting a hormonal IUD out, Dr. Shastri says, it may take people between three and six months to start having their regular periods again. But when it comes to birth control shots — which are administered every three months — patients may have to wait up to a year for their bodies to revert back to their normal cycles.
Plus, there's the fact that many people take hormonal birth control partly to help regulate medical issues related to their monthly cycle. And those conditions may still, on their own, affect fertility levels and cause period irregularities. For instance, polycystic ovary syndrome (PCOS) often causes irregular periods that are made more regular by using hormonal birth control. "When she goes off the pill, she'll revert back to her normal cycle," Dr. Shastri says, "which may be a 45- to 60-day cycle or she might not cycle at all."
Clearly, the idea of getting pregnant after going off birth control isn't exactly a simple one. So, if you do decide you want to stop taking your birth control, check in with your doctor about what you can expect on your journey to expecting.

More from Sex & Relationships