It’s happened to a lot of people, maybe even you. You get busy and forget to take your birth control pill. It might feel scary, but it doesn’t always mean you’ll get pregnant.
Birth control pills don’t prevent pregnancy 100% of the time. But they come close when taken as directed.
No method of birth control is foolproof, and it’s easy to make mistakes. So, it’s important to understand what birth control pills and other types of birth control do and how you can make them more likely to protect you from pregnancy.
How Effective Is Birth Control?
That depends on what type of birth control you’re using and, in the case of birth control pills, whether you take them as directed.
“When talking about birth control, we consider what is called ‘ideal use’ and ‘typical use,’ says Daniel Weinberg, MD, an obstetrician and gynecologist at Sentara Health in Harrisonburg, Virginia.
Ideal use means you take your birth control pills every day at the right time. Typical use means you might sometimes take them at a different time or miss a dose.
“Typical use odds of getting pregnant with the pill are about 10%,” Weinberg says. “Other methods that do not require the patient to remember things — like IUDs or Nexplanon – have lower rates of unintended pregnancy with typical use around 1%.”
Types of Birth Control Pills
Combined pills and mini pills are the only types of birth control pills. No matter which kind you use, it’s important to take them exactly as instructed, even on days you don’t have sex.
Combined pills
Also called combination pills, they contain man-made versions of two hormones, estrogen and progestin. A pack of combined pills usually has 21 to 24 days of hormones and four to seven days of reminder, or inactive, pills. Some packs have 26 days of hormones. Your period should start while you’re taking the inactive pills. It’s important to take all pills in the pack, including inactive pills, to make sure no active pills are missed.
You might take one pack of combined pills every month, or you can take the hormone pills continuously to delay or stop your periods. It’s generally considered safe to skip or stop periods, but you should discuss this option with your doctor and follow their instructions.
Mini pill
This type of birth control pill contains just one hormone, progestin. If you’re taking mini pills, it’s very important to take all 28 pills at the exact same time every day. If you’re late by just three hours, you have to use a backup method of birth control, such as a condom.
Do You Ovulate When You’re on Birth Control?
Combination birth control pills — those that contain both estrogen and progestin — stop you from ovulating. Progestin-only pills, also called mini pills, do the same. Just not consistently.
Because progestin-only pills don’t always stop ovulation, eggs sometimes partially mature. This may trigger swelling and pain in your ovaries, which you might mistake for ovulation.
Starting Birth Control Pills
The pill doesn’t start working right away. It may take up to seven days before it becomes effective. That’s why it’s important to use a backup contraceptive, such as condoms. Ask your doctor how long you need to use a backup method. Some recommend using one during your entire first pack.
If you just had a baby or you’re breastfeeding and want to take the birth control pill, you may have to wait for a certain period. Your doctor will let you know when it’s safe to start.
Remember, the pill doesn’t protect you against HIV or other sexually transmitted diseases (STDs). Use condoms every time you have sex, especially with new partners, to stay safe.
Missed Pills
You should take all your pills as directed, no matter what. Skipping a pill for any reason can increase your chances of becoming pregnant. If you’re tempted to skip a pill because they are causing side effects, talk to your doctor, but continue taking the pill. Many women who have side effects when they first start taking the pill feel better after three months.
If you miss one pill, there’s probably no need to worry. Just take it as soon as you remember and continue taking your next pill at the regular time. If it’s a mini-pill and it’s been more than three hours, use a backup method of contraception.
If you’re taking combined pills and miss two or more hormone pills, you should call your doctor. What you should do next will depend on what kind of pill you’re on, so they can advise you. No matter what, you should use a backup method of birth control, like a condom, as your chances of getting pregnant are much higher after you miss two or more pills.
Alcohol and Birth Control
Drinking alcohol doesn’t change how well birth control pills work. But since you need to take the pill every day at the same time for it to be effective, plan ahead if you’re going to drink. That’s because alcohol can affect your judgment and memory. A study published in the journal Psychology & Health found that risky drinking nearly doubled the odds of birth control failure.
Along with forgetting to take your pill, drinking too much could make you vomit. If you throw up within two hours of taking one, it's as if you never took it at all.
Birth control pills can also affect how your body processes alcohol. They slow down the rate at which your body absorbs it, which means it sticks around longer. The longer you’re under the influence, the more time there is to forget to take your pill.
Use reminder apps
Many apps can track your period, tell you how many pills you have left, and remind you when’s it’s time for a refill.
Take your pill early in the day
Take it when you first wake up or with your breakfast instead of in the evening, when you’re more likely to be tired and forget.
Carry backup protection
Always keep condoms and spermicide on hand. Ask your partner to support your efforts and do the same.
Other Reasons the Pill Can Fail
Forgetting to take your pill as directed isn’t the only reason it might fail. Certain medications can affect how well they work. These include:
- Anti-seizure medications
- Anti-HIV drugs
- Rifampin, an antibiotic used to treat tuberculosis
- St. John’s wort
Tell your doctor if you’re taking any of these medications. Other options may be a better fit.
Reasons Other Birth Control Options Can Fail
Whether pills, patches, or something else, no birth control method is foolproof.
Patches and rings
These work similarly to the birth control pill. You place a ring in your vagina (Annovera, NuvaRing) or a patch on your belly, upper arm, butt, or back (Xulane, Twirla). Like the pill, they’re over 99% effective when you use them exactly as instructed. If you don’t, they’re only 93% effective.
A vaginal ring can fail if:
- It’s been in less than three weeks.
- You take the ring out, or it falls out and isn’t replaced within two to three hours.
- You don’t remove it as instructed.
- It’s been exposed to sunlight or high temperatures.
The patch can fail if:
- You weigh more than 198 pounds.
- You forget to put one on.
- You remove it too soon.
- You take certain medications or have certain health conditions.
Birth control shot
Depot medroxyprogesterone acetate (Depo-Provera) contains progestin and is given every three months. With typical use, it’s effectiveness is 96% because not everyone gets the shot on time.
It’s important to get your follow-up shots every 12 weeks. If you wait longer, you’ll need to use a backup method of birth control for a week.
Birth control implant
Etonogestrel (Nexplanon) is a thin, matchstick-sized rod your doctor places in your arm. It releases hormones that prevent pregnancy for up to three years. It’s over 99.9% effective because you don’t have to remember to take it or use it the right way.
But if you’ve had it for three years and you still don’t want to get pregnant, you have to replace it.
IUDs
Your doctor places this in your vagina to stop sperm from reaching an egg. Like the implant, it’s more than 99% effective.
Once placed, you’re protected from pregnancy for about 3-10 years. There are two types of IUDs: copper (ParaGard) and hormonal (Kyleena, Liletta, Mirena, and Skyla).
Pregnancy is highly unlikely with an IUD. But if you do, it’s usually because the IUD slipped partly or completely out of your uterus.
Vaginal contraception
Also known as spermicide, you put this type of birth control in your vagina before sex to kill sperm so they can’t reach an egg and fertilize it. It comes in several forms, including:
- Foam
- Jelly
- Tablet
- Cream
- Suppository
- Dissolvable film
Each of these has to be used before sex and given time to be effective, usually 15 minutes. When used properly, spermicides are 70%-80% effective, but they work better when combined with a condom or diaphragm.
Normally, the vagina’s pH level rises during sex to help sperm travel to your uterus. A prescription nonhormonal gel called Phexxi keeps the pH level acidic, which kills sperm. It’s considered 86% effective when used correctly.
Barrier method
Diaphragms, cervical caps, and male/female condoms physically block sperm from entering your uterus. They’re much less reliable than hormonal methods of birth control.
The male condom, for example, is 98% effective with perfect use, but only 82% otherwise. That means 18 women out of 100 who regularly use condoms with their partner will end up pregnant within a year. Condoms often break or aren’t put on correctly.
Barrier methods work better if you pair them with spermicide.
Fertility awareness methods (FAMs)
Also called natural family planning and the rhythm method, these help you track your menstrual cycle so you know when you’re ovulating. To do this, take your temperature every day, check your cervical mucus, or chart your cycle on a calendar.
If you use at least one of these methods and you follow it perfectly, your chances of getting pregnant are less than 5%. But that can be tough for most people, which is why the typical effectiveness rate hovers around 75%.
If you use multiple FAMs together, they’re more likely to work. But this isn’t a good option if you have irregular menstrual cycles.
Early Signs of Pregnancy
One of the first signs you may be pregnant is a missed period. Other early signs of pregnancy include:
- Light bleeding or spotting
- Mood swings
- Food cravings
- Cramping or bloating
- Headaches or backaches
Getting pregnant on the pill symptoms
If you get pregnant while taking birth control, you may not know it, especially if your symptoms are mild. In fact, you may not notice anything until you start showing or feel the baby move.
If you do have symptoms, they’ll likely include nausea, vomiting, or feeling very tired. If you miss a period and have any of these symptoms, take a pregnancy test or talk to your doctor.
Takeaways
No method of birth control is 100% effective, but you can reduce your risk of pregnancy by following the directions. Some forms of contraception, such as the IUD and birth control implant, are 99.9% effective, while others, such as the pill, can be less effective if not used as directed. To reduce your chances of getting pregnant on birth control, always use a backup method, such as condoms. If you miss a period and think you may be pregnant, take a pregnancy test or see your doctor.
FAQs on Getting Pregnant on Birth Control
What are the odds of getting pregnant on birth control?
It depends on what type of birth control you use and whether you use it as directed. For example, when used as directed, the birth control pill is more than 90% effective. Other forms of birth control, such as IUDs or the implant, are often more effective because you don’t have to remember to take or use them.
How do you know if you’re pregnant while on birth control?
There may be early signs, such as missing your period, swollen or tender breasts, vomiting, or nausea. If you’re on birth control but think you may be pregnant, take a pregnancy test or see your doctor to know for sure.
Why do I have ovulation symptoms while on the pill?
Birth control pills stop ovulation so that you don’t become pregnant. But some types of pills can cause your eggs to partially develop. When this happens, you may feel pain and tenderness around your ovaries. These symptoms are less likely if you take your birth control pills exactly as directed.
