Oral contraceptives - also known as "the pill"- are 99% effective at preventing pregnancy. However, if you forget to take the pill, the effectiveness is reduced. Under typical circumstances, statistics show the pill is effective 93% of the time, which means about 7 out of 100 people get pregnant while on the pill. If you're concerned about oral contraceptive failure, it's helpful to know the signs of pregnancy while on birth control.
Pregnancy Symptoms While on the Pill
Early symptoms of pregnancy and side effects of oral contraceptives are very similar. So if you notice physical changes, it might be difficult to determine if it is a sign that you are pregnant or if the symptom is caused by your contraceptive.
Symptoms of early pregnancy and birth control side effects include:
- Breast tenderness
- Digestive issues (e.g., diarrhea, constipation)
- Frequent urination
- Missed period (depending on the type of birth control pill you're on)
- Mood swings
- Weight gain
Keep in mind that it is normal for spotting (light bleeding) to occur when you first start taking oral contraceptives. But spotting is also a common symptom of early pregnancy. If you typically have light menstrual cycles while you're on the pill, it may be possible to mistake early pregnancy spotting for an early period.
Taking a pregnancy test is the only way to know for certain if your symptoms are an early sign of pregnancy or a side effect of your oral contraceptive.
Home pregnancy tests can be purchased online and at most pharmacies and grocery stores. If you prefer, you can make an appointment with your healthcare provider to ask for a pregnancy test.
3 Key Facts About the Pill and Pregnancy
The side effects of birth control pills vary, depending on the type of pill you've been prescribed. When you first go on oral contraceptives, talk to your healthcare provider about what to expect. Then communicate any unusual symptoms if you become concerned.
Different Pills Have Different Effects
- Combined oral contraceptives. Contain both estrogen and progestin.
- Progestin-only pills. Also known as the mini-pill, these pills contain only progestin.
Both forms of oral contraceptives have the same rate of effectiveness but can cause different side effects. For example, progestin-only pills tend to cause spotting or breakthrough bleeding (bleeding between periods) more than combination-type pills.
Some People Experience No Symptoms on the Pill
Not everyone who takes birth control pills will experience side effects. Symptoms vary from person to person. Some people will experience symptoms for the first 2 or 3 months after starting the pill, as the body adjusts to the hormones. If you have any side effects that are impacting your quality of life or have questions about the way the pill is making you feel, talk to your healthcare provider.
The Pill Doesn't Increase the Risk of Birth Defects
Research shows that there is little risk of harm to an unborn baby if you continued to take the pill before you knew you were pregnant. If you were taking the mini-pill (progestin-only contraceptive), there is a slightly higher risk of the pregnancy being an ectopic pregnancy. This means the embryo may have implanted outside of the uterus, such as in a fallopian tube. Talk to your healthcare provider, who may order an ultrasound to provide an estimated due date and rule out ectopic pregnancy.
If you have taken a pregnancy test and the result is positive, discontinue the use of your birth control pills. If you're unable to get a pregnancy test but suspect you may be pregnant, stop taking the pill and use a different method of birth control (such as condoms) until you can get a pregnancy test to determine whether you are pregnant.
How to Prevent Birth Control Failure
If you're taking oral contraceptives, the best way to ensure they prevent pregnancy is to maintain a consistent schedule and take your pill at the same time every day. If it's challenging to remember to take your pill every day, you may want to set a daily reminder on your phone to alert you when it is time to take your contraceptive each day.
If maintaining a schedule to take a daily pill is challenging for you, you may want to talk to your healthcare provider about other forms of contraceptives, such as an intrauterine device (IUD), Depo shot, or a vaginal ring. To be extra cautious, you may want to consider using a condom in addition to your regular contraceptive to prevent pregnancy. This is especially important if you've recently started on birth control pills or other forms of contraceptives, as it may take a few days for hormonal birth control methods to work.
Lastly, remember that oral contraceptives are highly effective in preventing pregnancy, but some people do get pregnant while taking the pill. Forgetting or skipping a dose can increase the likelihood that you will become pregnant. If you are pregnant or think you are pregnant despite your use of oral contraceptives, visit your healthcare provider. They can confirm your pregnancy via ultrasound, provide you with the support and medical care you need, and answer any questions you may have.