If a person taking birth control pills misses a period, they may wonder whether they are pregnant. However, a range of other factors may be responsible for a missed period while taking oral contraceptives.
Birth control pills are a popular and practical method of contraception. There are several types, and each contains different combinations of hormones that can affect the menstrual cycle.
The term for the absence of an expected period is amenorrhea. Experiencing this while taking oral contraceptives is common.
This article discusses what factors can cause a person to miss a period while taking birth control pills.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.
- prevent ovulation
- thin the uterine lining, preventing fertilized eggs from implanting
- cause the cervical mucus to thicken, preventing sperm from reaching the egg
Birth control pills are typically organized by week, with the pills for the first 3 weeks containing hormones and the pills of the final week containing no active medication. These placebo pills simply help a person to remember to take a pill each day.
When taken correctly, birth control pills are collectively estimated to be around 99% effective.
However, it is not uncommon for a person to miss a dose. Also, if a person vomits, they may not fully ingest the pill. These factors can reduce the effectiveness and may lead to an increased risk of pregnancy or irregular bleeding.
Learn more about birth control.
There are various factors that can lead to a missed period while taking birth control.
The type of pill
Some birth control pills can cause periods to stop or become irregular. Other types, sometimes called continuous birth control, can cause a person to have only four periods a year.
Everyone is different, and the effects of pills are not always predictable. If a person has recently started taking a new pill, the body may need time to adjust, and this can cause a missed period.
Rapid weight loss
Losing weight quickly can strain the body. Sudden or excessive weight loss can cause a person’s periods to stop.
Severely restricting calorie intake can also cause the body to stop producing the hormones necessary for ovulation.
Overweight and obesity
PCOS can cause various symptoms. However, a common symptom is irregular menstruation. This can include missed periods. If a person misses a period and pregnancy is not the cause, a healthcare professional may recommend further testing for conditions such as PCOS.
Pregnancy is one of many reasons a person can miss a period.
While oral contraceptives are an effective method of birth control, they are only 99% effective when taken exactly as recommended. This means there is a very small risk that a person can still get pregnant when taking birth control pills correctly.
Anyone who is sexually active and has missed a period or had only light spotting should take a pregnancy test or contact a healthcare professional.
The likelihood of becoming pregnant increases if a person misses a dose.
Other early signs of pregnancy include:
- nausea or vomiting
- breast tenderness
- low energy level and sluggishness
- aching in the lower back
- urinating more frequently
If a person has not had an expected period and experiences any of the other symptoms of pregnancy, they should take a pregnancy test.
Learn more about early signs of pregnancy.
The birth control pill regulates the menstrual cycle. Most types work in 4-week cycles. A person taking these types of pills can typically expect a period every 28 days.
Depending on the type of birth control, some people may experience periods more frequently. For others, periods may stop completely. A person should discuss the various types of oral contraceptive options with a healthcare professional.
There are various reasons a person may experience a missed period while taking birth control pills.
One way to determine whether a missed period is due to pregnancy is to take a pregnancy test. A person can buy one to take at home or make an appointment with a healthcare professional.
Other causes of a missed period include the type of birth control, overexercising, and obesity.
Missed periods can also signal underlying medical conditions, such as PCOS. If periods remain irregular or stop unexpectedly, a person should contact a healthcare professional.