- A home pregnancy test is usually the first step after a missed period, especially after recent unprotected sex, and repeating the test later may be needed if it was taken too early.
- Late periods can be triggered by stress, hormonal shifts, intense training, restrictive diets, or birth control changes, and cycle-supporting steps may include easing workout intensity, managing stress, and keeping a balanced diet.
- Medical evaluation is recommended when a period is absent for more than 3 months, when the cause is unclear, or when pregnancy is ruled out but symptoms raise concern (such as severe pelvic pain or signs of ectopic pregnancy).
What to do when periods are late often starts with ruling out pregnancy, especially after recent unprotected sex. An over-the-counter pregnancy test can help confirm whether pregnancy is the reason for the delay.
However, a late period is not always caused by pregnancy. Stress, hormonal changes, intense exercise, restrictive diets, birth control use, and conditions like polycystic ovary syndrome or thyroid disorders can delay menstruation for days or even months.
Knowing what to do when periods are late also means recognizing when medical evaluation is needed. If a period is absent for more than three months or the cause is unclear, a gynecologist may order blood tests to check hormone levels and recommend treatment to regulate the cycle.
How long can a period be delayed?
A period can be delayed by about five days and, in some cases, up to one or two months. If your period has been absent for more than three months, it may indicate amenorrhea (a lack of menstruation). When pregnancy has been ruled out, the underlying cause should be assessed by a gynecologist.
What should I do if my period is late but my pregnancy test is negative?
According to the U.S. Department of Health and Human Services Office on Women’s Health, home pregnancy tests can be almost 99% accurate when used correctly, and results tend to be more accurate after the first day of a missed period.
A false negative pregnant test result can occur if the test is taken too early, if the menstrual cycle is irregular, or in cases of ectopic pregnancy.
It’s also possible for hormonal imbalances to delay menstruation, even in women who usually have regular cycles, and this doesn’t necessarily indicate pregnancy.
What causes a late period?
The most common causes of a late period are:
1. Pregnancy
One of the most common reasons for a missed or late period is pregnancy. During pregnancy, hormonal changes stop the shedding of the endometrium, which normally causes menstruation.
In this case, the delay is often accompanied by symptoms such as abdominal bloating, mild cramps, fatigue, breast tenderness, and darkening of the areola.
2. Intense physical activity
Intense physical activity can affect hormone levels, especially in athletes or people training hard for competition. For instance, consistently elevated prolactin levels from vigorous exercise can delay menstruation. Regular exercise is essential for health, but overtraining should be avoided.
3. Restrictive diets
Some restrictive diets can cause hormone fluctuations that disrupt your menstrual cycle. When you significantly reduce your food intake, your body conserves nutrients for essential functions, which can delay or even stop your period.
4. Reproductive health conditions
Reproductive health conditions such as endometriosis, polycystic ovary syndrome (PCOS), or uterine fibroids can affect your sex hormone levels, sometimes causing your period to be delayed.
5. Alterations in the hypothalamus and hippocampus
The hypothalamus and hippocampus in the brain help regulate sex hormones. When these parts of the brain don’t function properly, they can disrupt hormonal balance and cause menstrual changes, such as periods that come earlier or later than usual.
6. Continuous-use birth control
Continuous-use birth control pills and other hormonal methods release steady levels of hormones without breaks. This prevents menstruation, though some women may experience occasional light or breakthrough bleeding.
7. Perimenopause
As menopause approaches (a stage called perimenopause), it’s normal for menstrual periods to become less regular and gradually stop. Women who experience menopause earlier than average may not immediately recognize that they’re entering this transition.
8. Postpartum
After childbirth, menstruation typically resumes once breastfeeding has stopped. However, it’s still important to use contraception during this period to prevent unintended pregnancy.
9. Stopping contraceptives
After stopping hormonal contraceptives such as the birth control pill, birth control implant, or Depo Provera injections, some women may find that their periods take up to six months to return to a regular cycle. This delay is normal and usually not a cause for concern.
10. Hormonal changes in adolescence
During adolescence, the endocrine system is still maturing, and hormonal fluctuations are common. As the body adjusts to changing hormone levels, ovulation may not occur regularly, leading many teens to experience irregular or delayed periods.
Adolescents who reach the age of 16 and have not yet started menstruating should see a gynecologist. This condition, known as primary amenorrhea, may be caused by structural differences or abnormalities in the reproductive organs, such as a vaginal septum or the absence of a uterus.
11. Stress and anxiety
Stress and anxiety can increase levels of cortisol in the blood. This hormone affects how the hypothalamus functions and can interfere with the release of estrogen and progesterone, two hormones essential for regulating the menstrual cycle.
When will my period come?
Enter your cycle information below to calculate when your period is due:
This calculator should only be used as a tool and does not replace an appointment with your gynecologist or other healthcare provider.
What to do if your period is late
If your period is late, start by taking a home pregnancy test from the pharmacy. According to the American College of Obstetricians and Gynecologists (ACOG), going 3 months or longer without a period can be considered amenorrhea and should be evaluated by an OB/GYN, especially when pregnancy has been ruled out.
Your gynecologist may order blood tests to check progesterone and prolactin levels, which can help determine the cause of the delay and guide the most appropriate treatment. In some cases, your doctor may prescribe medication to help start your period.
Depending on what is causing your period to be delayed, you may need to reduce the intensity of your workouts, rest more, manage stress, and follow a well-balanced diet rich in vitamins and minerals. All of these factors help support a regular menstrual cycle.
It’s also recommended to see your doctor regularly to check for potential health conditions such as polycystic ovary syndrome (PCOS), endometriosis, eating disorders like anorexia or bulimia, and thyroid disorders (hyperthyroidism or hypothyroidism), as all of these can affect your menstrual cycle.
How to regulate your menstrual cycle
Certain steps can help prevent delayed periods and support a regular menstrual cycle, such as:
- Maintaining a healthy lifestyle with regular exercise and a balanced diet rich in fruits and vegetables;
- Using the contraceptive pill, which can help regulate the menstrual cycle;
- Avoiding extreme or restrictive diets, as these can harm your health and disrupt your cycle;
- Following your prescribed treatment plan if you have polycystic ovary syndrome (PCOS) or thyroid disorders;
- Maintaining a healthy weight.
While these measures can help keep your cycles regular, you should still consult a doctor if your periods become irregular.