Missing your period can be worrisome when on birth control.
You may be wondering if you’re pregnant or if there’s something wrong with the birth control method you’re using.
In this article, we’ll explore the various reasons why you might miss your period while taking birth control pills, ways to track your period, and when you should consider visiting a doctor.
How Do Birth Control Pills Work?
Hormonal birth control is an effective way to prevent pregnancy and treat certain medical conditions.
When an egg is released from the ovary, is fertilized by sperm, and implants in the uterus, this leads to pregnancy.
Hormones in your body control the release of the egg from the ovary, called ovulation, and prepare your body to accept the fertilized egg.
Birth control pills contain either a small amount of estrogen and progesterone hormones or just progesterone. These hormones prevent pregnancy in a few ways.
For starters, they stop ovulation from occurring so your body will not release an egg to be fertilized.
They also change the cervical mucus to make it difficult for the sperm to travel up the vagina to get to the egg.
In addition, they can also change the lining of the uterus, making it difficult for a fertilized egg to implant.
So, why is there a risk of missing your period on birth control pills?
Reasons for Missed Period on Birth Control
There are many reasons why you might miss your period on birth control.
The hypothalamus is the part of the brain that controls the hormones involved in the menstrual cycle.
When the hypothalamus is working properly, it releases chemicals that cause the pituitary gland to stimulate other hormone-producing parts of the body, including the ovaries, which release hormones called estrogen and progesterone.
These hormones induce a period.
When the body is under stress, it can release a hormone called cortisol.
Cortisol can block the hypothalamus from releasing the chemicals that trigger your period.
So, if you’re experiencing increased stress, you may miss your period whether you’re on hormonal birth control or not.
If you are not consuming an appropriate number of calories or if your diet is lacking in certain nutrients, it can affect the hormones responsible for causing a period.
This often happens to people with eating disorders, such as anorexia nervosa or bulimia, or athletes.
On the other hand, eating too much can also lead to a missed period.
Gaining weight can cause the body to produce extra estrogen, which can cause irregular periods or cause them to stop entirely.
Birth Control Changes
Changing forms of birth control can also lead to a missed period.
If you’ve recently switched from a combination pill to a progesterone-only pill (minipill) or from one brand of combination pill to another, the different hormone levels can lead to a missed period as your body adjusts to the hormonal change.
The minipill may also cause irregular or absent periods because of the way the hormone is dosed.
Some pills (e.g., SeasoniqueⓇ) are meant to be taken continuously for several months and you will not have a period, or will have only light spotting, while taking them.
Physical stress can also disrupt your menstrual cycle—even if you are on birth control.
High-intensity exercises can increase cortisol levels, which can interfere with the production of hormones that induce a period.
High-level athletes are at particular risk of missing a period due to excessive or over-intense exercise and not eating enough for their energy needs.
Hormonal imbalances in the body can also cause you to miss your period while taking birth control pills.
There are many hormonal imbalances and disorders that contribute to irregular or absent periods, but three of the most common disorders include:
- Polycystic ovary syndrome (PCOS): This condition causes the body to produce more androgen than is normal, which, in turn, causes cysts to grow in the ovary. These cysts create a hormonal imbalance that can cause irregular ovulation or prevent ovulation. Some people with PCOS either experience irregular periods or their periods stop entirely, also termed amenorrhea.
- Thyroid disorders: The thyroid is regulated by the hypothalamus and is responsible for the production of some of the hormones that influence puberty and menstruation. Both an overactive thyroid (hyperthyroidism) and an underactive thyroid (hypothyroidism) can delay your period or stop it entirely.
Pregnancy is one of the most common and natural causes of a missed period.
During the menstrual cycle, hormones cause the lining of the uterus to thicken.
This makes a safe place for a fertilized egg to land and implant, beginning a pregnancy.
A period happens when the uterus sheds this lining because a fertilized egg did not implant there.
If the uterus is implanted with a fertilized egg, the body holds on to the lining of the uterus, which is why periods stop.
While hormonal birth control is more than 99% effective at preventing pregnancy when taken as directed, pregnancy may still occur while you are on it, especially if you miss doses or take it incorrectly.
Breastfeeding and Menopause
Breastfeeding and menopause are other natural, common reasons for missing a period.
When a person is breastfeeding, their body releases hormones that prevent another pregnancy.
This can cause irregular or missed periods.
During menopause, hormone levels begin to drop and the body stops ovulating regularly, which can lead to changes in your menstrual cycle and irregular or absent periods.
Tracking Your Period
If you are concerned about why you missed your period on birth control, tracking your monthly cycle can help identify your normal patterns and may give your provider some clues about the underlying reason.
It can also help you determine whether a pregnancy test is a good idea.
When to See a Provider
If you are concerned about why you missed your period on birth control, it is important to speak with a doctor or healthcare provider.
There are many potential causes of a missed period, and only a medical professional can help you determine the cause and find a solution.
Some of the reasons to see a doctor include:
- You missed more than one period in a row: While this can be a normal side effect of your birth control method, if it happens frequently, you should be evaluated to make sure that you are not pregnant or suffering from another underlying condition.
- You are experiencing other symptoms, such as pain, excessive bleeding, or fever: These could be signs of a more serious problem and need to be addressed right away.
Missing a period can be a cause for concern, but it is often nothing to worry about, and is sometimes just a side effect of your birth control type.
However, if you are concerned about why you missed your period on birth control, tracking your menstrual cycle and talking to a doctor or healthcare professional can help you determine the cause and find a solution.
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Frequently Asked Questions
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
Contraception: Hormonal contraceptives. (2017.)
The Prevalence of Polycystic Ovary Syndrome: A Brief Systematic Review. (2020.)
What causes amenorrhea? (2017.)
General Information/Press Room. (n.d.)
Adherence to the oral contraceptive pill: the roles of health literacy and knowledge. (2020.)