Does The Morning-After Pill Always Work? There's One Time Of Month When It Doesn't

You might know (though you'd be forgiven if you don't, given the sorry state of sex ed in this country) that if you think your birth control method may have failed, you can take the morning-after pill to prevent pregnancy. However, you may not have known that this doesn't work every day of the month. There are certain days in your cycle where the morning-after pill will do very little.

"Emergency contraception pills work by delaying ovulation — if it hasn't already happened or if it isn't just about to happen," Anna Druet, Researcher and Science and Education Manager at Clue, tells Bustle. Ovulation is the stage in the menstrual cycle when the egg makes its way from the ovary down to the fallopian tube, where it can be fertilized if it makes contact with sperm. The egg stays in the fallopian tube for about 24 hours at most, reproductive endocrinologist Aimee Eyvazzadeh, MD tells Bustle. This is the time in your cycle when you're most fertile.

"That means if [morning-after pills are] taken just before ovulation, or just after ovulation has happened, when you are still fertile, they won't be effective," says Druet. But how, then, do you know when you're ovulating? And what do you do if you think you may have gotten pregnant during ovulation?

How To Know When You're Ovulating

There's no way to be 100 percent sure when you're ovulating, since your cycles all vary a bit in length. However, you can track your period to get an estimate. Period-tracking apps like Clue and MyFlo can predict what phase you're in after you record what days your period takes place for several cycles. You can also use Americanpregnancy.org's ovulation calendar, though it also won't be completely accurate because, again, your cycles may not always be the same length.

Ashley Batz/Bustle

You can also look for some physical signs of where you are in your cycle. Obviously, if you're menstruating, you're done ovulating. If you're producing more vaginal discharge than usual, that's a sign that you are ovulating. You might even be able to feel yourself ovulating. For some, it feels like a momentary discomfort on one side of the pelvis. Your basal body temperature also shoots up right after ovulation.

What To Do If You May Have Gotten Pregnant While Ovulating

So, then what? If you need the morning-after pill and are not sure if it'll work, there are a few other options you can try, Dr. James Trussell, Professor of Economics and Public Affairs, Emeritus at Princeton University at creator of not-2-late.com, tells Bustle. "Insertion of a copper IUD is the most effective option and will be effective any time in the cycle," he says. An IUD is a device that gets inserted into the uterus to serve as hormonal birth control.

Of course, an IUD is very different from the morning-after pill in that it lasts for several years (or until you take it out), but it may be worth it if you're looking for the most effective pregnancy prevention method possible. In fact, copper IUDs have a 90 percent success rate if inserted within a week after sex, says Eyvazzadeh. "The copper in the IUD causes an inflammatory response in the cavity that prevents implantation from occurring if an embryo is already in the fallopian tube," she says.

If you're going to stick with an emergency contraception pill, Trussel says your best bet is Ella, because other levonorgestrel pills are less effective. Ella won't work every day of the month, but it will work for about a day longer than other pills, says Druet. Regardless of what method you choose, Trussell recommends taking a pregnancy test if your next period doesn't come.

But obviously, it's best not to get into this position in the first place. "Talk to your doctor about long-term contraception so you don't stress yourself out over these emergency types of situations," says Eyvazzadeh. "See about having [the morning-after pill] on hand at home so you don't have to make panicked phone calls to your OB/GYN."