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The birth control pill can be your BFF when it comes to enjoying your sex life free from worry. It’s the most popular method of reversible contraception in the United States, used by 12.6 percent of women ages 15 to 49.

While it’s not the right solution for everyone, many people rely on the pill as their primary form of birth control and family planning. But it’s not perfect, and there’s still a slight chance you could get pregnant on the pill — especially if you miss a dose or two.

Knowledge is power when it comes to birth control. The more you understand about how the pill works, the better you’ll be at taking it effectively (and thus not getting pregnant until you actually want to get pregnant).

Here’s how the science shakes out and how you can minimize your risk.

In an ideal world, the birth control pill does its job pretty freaking well. Planned Parenthood estimates that when taken perfectly, the pill is 99 percent effective at preventing pregnancy.

It does this by stopping ovulation, which means an egg isn’t released from your ovary each month to be fertilized by sperm.

The birth control pill also thickens your cervical mucus, making it less hospitable for sperm to reach an egg. It essentially turns your uterus into a fiercely guarded surveillance zone, unsurvivable to outside invaders (which, TBH, sounds badass).

There are two types of birth control pills: combination pills and progestin-only pills.

Combination pills, the most popular type, contain two hormones: estrogen and progestin. For people who can’t take estrogen (likely due to family history of blood clots or migraine), the progestin-only pill, sometimes called the mini pill, is another option.

Regardless of which type of pill you’re taking, it’s best to take it at the same time every day. Making it part of your daily routine can help prevent missed doses and ensure that the pill is as effective as possible.

If you use a progestin-only pill, it’s essential to take it within the same 3-hour window every day.

But let’s be real: Humans aren’t perfect. Sometimes you forget to pick up your refill pack or you miss a pill one day and take two the next.

According to Planned Parenthood, the average person takes the pill at a 91 percent accuracy rate, meaning 9 of every 100 people who use the pill will get pregnant.

Those odds aren’t great, which is why it’s super important to be diligent about taking your pill on schedule.

Skipping a day

It happens to the best of us. Even when you’re on a rigorous schedule of taking your pill each day, you’ll inevitably have times where you get out of your routine and just forget.

If you miss a pill, it’s OK to take two the next day to get back on track. If you miss just one combination pill, you’re safe without a backup contraceptive.

But if you miss one progestin-only pill or more than one consecutive combination pill, use a condom or abstain from sex for the next week.

This is all super confusing, we know. If you need more details on what to do when you miss a pill, here’s a handy guide from Cornell Health that breaks it all down.

Taking them at random times each day

For maximum effectiveness, take the pill at the same time every day. This is especially important with the progestin-only pill, which must be taken within the same 3-hour window each day.

Rifampin (antibiotic)

Most antibiotics won’t mess with your birth control’s effectiveness, but Rifampin is an exception. Talk with your doctor if you’re concerned about an antibiotic prescription.

Griseofulvin (antifungal)

Antifungals don’t usually interfere with birth control, but this particular medication is a special case.

St. John’s wort

This herb, which is often used to treat depression and symptoms of menopause, can contribute to irregular periods and breakthrough bleeding when taken with birth control pills.

Certain HIV and anti-seizure medications

Before starting a new prescription of this nature, check with your healthcare provider to make sure it won’t interact with your birth control in any way.

Take it daily, including the placebo pills

Getting into a routine is the easiest way to ensure you won’t forget a pill. Even if the last week of your pill pack is placebos (which you technically don’t need to take), it’s best to take them anyway to stay on schedule.

Set a reminder

Having a daily alarm on your phone will help you remember when to pop your pill.

Use multiple methods of contraception

A barrier method, like a condom or diaphragm, can be used alongside the pill as another line of defense. Condoms are also the best way to lower your risk of contracting STIs.

If you’re in a monogamous relationship and trust your partner, you can also rely on the withdrawal method — but don’t use this as your only birth control. According to the CDC, it’s only 78 percent effective on its own.

Here’s some surprising scientific intel for you: There’s evidence that the birth control pill can be used to help people get pregnant. Before you say “Huh?” and start to worry, hear us out.

A 2008 study found that using birth control leading up to in vitro fertilization could actually make it easier to conceive quickly.

And in a 2000 study, by suppressing ovulation for months and then restarting it, some IVF users were able to conceive within just a few menstrual cycles. The existing research still mostly pertains to IVF, not natural conception.

That said, the birth control pill can also mask menstrual irregularities that may make it difficult to conceive. Some people have irregular periods in the first few months after they stop taking birth control.

If your periods were inconsistent before starting the pill due to polycystic ovary syndrome, stress, weight changes, or other causes, they may still be irregular once you ditch the contraceptive.

Before going off birth control, talk to your doctor about any specific concerns you have.

Been taking the pill, but worried that something went wrong and you might be pregnant?

Early pregnancy symptoms include morning sickness, a missed period, breast tenderness, and fatigue. These symptoms can also come from other causes, including stress, weight changes, or an infection.

To find out for sure, take an at-home pregnancy test. These tests detect elevated hCG, a hormone that will show up in your urine and blood around the 2-week mark after conception.

But don’t rush to quit your birth control the second you suspect you’re pregnant. There’s no known risk of fetal development issues from taking birth control at this early stage. If you find out you’re actually pregnant, then you can stop taking your pill.

In the unlikely event that you get pregnant while taking the pill, the pregnancy is slightly more likely to be ectopic if you’re taking a progestin-only pill. An ectopic pregnancy occurs when a fertilized egg attaches somewhere outside the uterus, typically in the fallopian tubes.

Ectopic pregnancy is very rare (only 5 in every 1,000 pregnancies) but requires immediate medical attention. Symptoms include those typical of early pregnancy, as well as sharp and severe abdominal pain or cramping and vaginal bleeding.

All birth control pills ultimately protect against ectopic pregnancy by greatly decreasing your overall chances of getting pregnant.

tl;dr

  • While the birth control pill is 99 percent effective if taken perfectly, most people take it at about 91 percent effectiveness. This means 9 out of every 100 people who rely on pill will get pregnant.
  • There are two types of birth control pills: combination pills and progestin-only pills. It’s best to take the pill at the same time each day. This is especially important for progestin-only pills, which must be taken in the same 3-hour window every day.
  • If you miss a pill one day, you can take two the next day — but, depending on the type of pill, you may need to use backup contraception for a week or so afterward.
  • Certain medications or supplements, including the antibiotic Rifampin and the herb St. John’s wort, can decrease your birth control’s effectiveness. Talk with your doctor for details.
  • Take your pill on a schedule to develop a solid habit, and use a backup method like condoms or withdrawal for another layer of protection.
  • Studies have shown that taking the pill may help some women conceive through IVF, but so far, this research doesn’t apply to natural conception.
  • If you find out you’re pregnant on the pill, don’t worry — it’s not known to cause any fetal development issues. Simply stop taking the pill once you’ve confirmed you’re actually pregnant.