Pregnancy symptoms while on birth control pill

Key takeaways:

• Hormonal birth control is very effective in preventing pregnancy, and it rarely fails. 

• You have to use hormonal birth control correctly to make sure it’s as effective as possible.

• In the rare case you become pregnant while using birth control, the hormones are unlikely to harm your pregnancy.

Hormonal birth control is extremely effective. But there may be times when pregnancy can occur. An accidental pregnancy can happen if you don’t use your birth control properly or if it isn’t the best option for you.

And it’s understandable if that raises a lot of questions. When you start birth control, you get a lot of information about how those hormones will affect you. But you also may be wondering how they affect a pregnancy, should the unexpected occur. 

How does birth control work in the body?

When you have a normal menstrual cycle, your brain releases hormones that allow your body to prepare for a possible pregnancy. One of your ovaries releases an egg. Next, the mucus of your cervix thins so sperm can pass through. And the lining of your uterus thickens to prepare for the fertilized egg to implant. When you don’t have a fertilized egg, the lining sheds and you see it as your monthly period.

Hormonal birth control interrupts this process. When you use birth control, your ovaries will not release an egg. Your cervical mucus becomes thick. And it becomes harder for a fertilized egg to implant in the lining of your uterus.  

Can you get pregnant while taking birth control?

Yes, it’s possible. Birth control is very effective. But the only way to guarantee you won’t get pregnant is to not have sex. 

When providers describe the effectiveness of birth control, they use two numbers

1. Perfect use is how effective it is when you use it correctly every time. 

2. Typical use is the effectiveness in the real world, or how effective the method is when most people use it. 

Most hormonal birth control has a less than 1% failure rate with perfect use. But, depending on the method, typical failure rates range from 7% to 9%.

The more effective birth control methods are the ones that don’t need you to do anything for them to work. When you’re responsible for the hormones, it’s possible to miss doses or poorly administer them. Long-acting birth control often removes this step and tends to have lower failure rates.

Here’s a list of some common forms of hormonal birth control, failure rates, and reasons why they fail. 

Pill

Pills are the most common form of hormonal birth control. There are two different types of pills, but they’re similarly effective. The combination pill contains both estrogen and progestin. The “mini-pill” only has progestin. 

You have to take the combination pill every day. And you have to take the mini-pill around the same time every day for it to be effective. If you miss a pill or take one late, the chance of pregnancy increases. Pills have a failure rate of 7% with typical use. 

Patch

The patch is a square plastic film that sticks to the skin. You need to change it once a week. In order to be effective, the whole surface of the patch has to stick to your skin. If all or part of it lifts off, you may not get the full dose of medication. The patch doesn’t prevent pregnancy for 7% of the people who use it.

Ring

The ring is a flexible, plastic loop placed in the vagina. You change it once a month. If you keep  the ring out for an extended period of time or don’t replace it on time, your risk of pregnancy increases. The failure rate is 7%.

Shot

The shot is an injection of progestin. You get it once every 3 months. There’s a type that your provider gives you and another that you can give yourself. Because it is longer acting, it has a lower failure rate. But you still have to get your shots on time for it to work. It has a 4% failure rate.

Long-acting reversible contraceptives

Long-acting reversible contraceptives (LARCs) are the most effective forms of birth control. They include the IUD (intrauterine device) and the implant. 

The IUD is made out of plastic or copper and may or may not contain the progestin hormone. Your healthcare provider inserts it into your uterus through the vagina. And, depending on the type, you can use it for 3 to 10 years.

The implant is a plastic rod that contains progestin. Your healthcare provider inserts it under the skin of the arm. You can use it for 3 years. 

LARCs have a failure rate of less than 1%. This is likely because it requires no action on your part. After insertion they successfully prevent most pregnancies.  

How many pills do you have to miss to get pregnant?

Experts aren’t exactly sure how many pills you have to miss to get pregnant. But, if you miss one or more active pills (with hormones), you may be almost three times as likely to have an unintended pregnancy. The more pills you miss, the greater your risk of pregnancy. If you miss pills for more than 7 days, there’s a high risk that one of your ovaries will release an egg. 

The risk of getting pregnant not only depends on how many pills you miss — but when you miss them. A very important time period is the week of placebo pills. Placebo pills are inactive pills with no hormone in them at the end of your pack (in the fourth week). You don’t have to worry about getting pregnant if you miss the placebo pills. But your risk of getting pregnant is especially high if you miss pills before (in the third week) or after your placebo pills (in the first week). 

How to know if you’re pregnant while taking birth control

A missed period is one of the first signs of pregnancy for many people. But when you’re taking birth control you may have stopped tracking your periods. So you might not notice if you miss one. Or your periods may become less regular or go away completely. 

So you may have to use clues other than your period to figure out if you should take a pregnancy test. Other common symptoms that can signal a possible pregnancy are:

• Nausea and vomiting

• Breast tenderness

• Extreme tiredness

• Sudden and unusual food cravings or dislikes

If you have these symptoms and you've missed any pills, you may want to strongly consider taking a pregnancy test. When in doubt, you should ask your healthcare provider.

What to do if you test pregnant while using birth control

First, try not to panic. Make an appointment with a provider to confirm your pregnancy. This will include testing to make sure your pregnancy is developing normally and to determine how far along you are. Then you can talk about next steps regarding your pregnancy. 

Do hormones hurt the baby if you’ve unknowingly been taking birth control during a pregnancy?

Most studies show there’s no increased risk of harm to an unborn baby from most forms of birth control. This includes birth defects, preterm delivery, and other risks. 

The exception to this is if you get pregnant while you have an IUD in place. In this case, you may be at risk for miscarriage, preterm delivery, or infection. Your provider may advise removal of the IUD. But, remember, getting pregnant while using the IUD is very rare.

What are the risks of continuing birth control while pregnant?

While there’s little evidence that hormones from most forms of birth control will harm a pregnancy, there’s no reason to continue them. Your healthcare provider will encourage you to stop taking them. That’s because the purpose of birth control is to prevent pregnancy. 

That said, once a pregnancy has occurred, hormonal birth control won’t abort a pregnancy or cause miscarriage. 

The bottom line

Hormonal birth control is very effective in preventing pregnancy. Make sure you’re using the best one for you so you'll be less likely to miss a dose. Missing doses will increase the likelihood of a pregnancy. In the case you become pregnant while taking birth control, the hormones are unlikely to harm the pregnancy. If you’re taking birth control and think you may be pregnant, contact your provider to find out for sure. They can help you plan the next steps.  

Centers for Disease Control and Prevention. (2022). Contraception.

Charlton, B. M., et al. (2016). Maternal use of oral contraceptives and risk of birth defects in Denmark: Prospective, nationwide cohort study. British Medical Journal.

Curtis, K. M., et al. (2006). Effective use of hormonal contraceptives: Part I: Combined oral contraceptive pills. Contraception.

Guilbert, E., et al. (2008). Missed hormonal contraceptives: New recommendations. Journal d'Obstetrique et Gynecologie du Canada.

Piriyev, E., et al. (2020). Case report: Pregnancy while using an IUD. Obstetrics and Gynaecology Cases - Reviews.

Rosenberg, M. J., et al. (1995). Use and misuse of oral contraceptives: Risk indicators for poor pill taking and discontinuation. Contraception.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

Was this page helpful?

Subscribe and save.

Get prescription saving tips and more from GoodRx Health. Enter your email to sign up.

By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.

How do you know if you are pregnant while on the pill?

Is it possible to be pregnant on birth control and not know?

What will happen if you get pregnant while on birth control?

Can pregnancy occur while on birth control pills?