WHY IS MY PERIOD LATE? 15 Possible Reasons

A delayed or missed period is usually the first sign of pregnancy, however, dozens of other causes may explain why your period did not come on the expected day.

In general, a few days of menstrual delay can occur even in women with a regular menstrual cycle, without this having any clinical relevance.

In non-pregnant women, even when menstruation does not come in a given month, the chance of this being important is small. Stress, miscalculations, changes in the contraceptive method, urinary tract infection and other less relevant situations are often the most common causes.

However, when menstruation does not come for 3 consecutive months, the woman is said to have amenorrhea. In this case, once pregnancy is excluded, some diseases may be the cause.

In this article, we will address 15 common causes for menstrual delay. They are as follows:

  • Pregnancy.
  • Stress and anxiety.
  • Interruption of the contraceptive pill.
  • Infections or diseases.
  • Calculation errors.
  • Recent changes in body weight.
  • Obesity.
  • Excessive weight loss or eating disorders.
  • Strenuous physical activity.
  • Thyroid problems.
  • Breastfeeding.
  • Polycystic ovarian syndrome.
  • Menopause.
  • Recent start of the menstrual cycle.
  • Amenorrhea.

So, if your period is missing, see what situation you fit into.



Every sexually active woman who has menstrual delay should unfailingly think about pregnancy. If the period is missing, pregnancy should be the first hypothesis to be ruled out, even in women who report using contraceptive methods, such as a condoms or birth control pills.

Do not expect to have nausea, enlarged breasts, food cravings, abdominal pain, or increased urination before a missed period. The menstrual delay usually appears with 3 or 4 weeks of pregnancy, while the other symptoms usually appear only after the 4th or 5th week.

The cessation of menstruation is usually the first symptom of pregnancy. However, since about 1/3 of pregnant women have light bleeding in the first trimester, many of those women think that their periods are coming normally. So, if your period is late, and a few days after you begin to have a vaginal bleeding somewhat different from what you are accustomed to having during the menstrual period, a pregnancy can be the cause.

There is no safer way to confirm – or rule out – an ongoing pregnancy than to take a pregnancy test. The current tests are already able to identify a pregnancy with only one day of delayed menstruation. However, these tests are more reliable if performed after one week of your missing period. Blood BhCG concentration is the most reliable test, but the drugstore pregnancy test is easier to do and also has a high accuracy rate (see: WHAT IS BETA hCG – The Pregnancy Test).


The menstrual cycle is easily influenced by factors other than the reproductive system. Emotional factors are enough to delay your menstruation for a few days. Excessive stress or anxiety can negatively affect your hormone production, which is regulated by the hypothalamus, a part of the brain. Stress can even cause you not to ovule in a given cycle, stopping your menstruation from coming that month.

When we talk about stress, it includes situations that are common to many people, such as excessive work, professional problems, financial or family issues, important exams in the near future, defense of a thesis, a sick child at home, etc. Abrupt changes in working hours, as well as a constant need to work at dawn, can also disrupt the sleep cycle and interfere with the normal ovulatory cycle.

If you do not wish to get pregnant at a given time, and something wrong has occurred in one of your sexual relationships, such as a broken condom or forgetting to take the pill correctly, the stress generated by the risk of becoming pregnant may also be big enough to delay your period.

This process can also become a snowball, because anxiety leads to menstrual delay which, in turn, causes even more anxiety. In these cases, if menstruation is already 2 or 3 days late, the ideal thing is to do the pregnancy test as soon as possible, to break this vicious cycle.


Women who regularly take oral contraceptives menstruate regularly. However, if after a few years of using the pill, you decide to suspend it, it is possible that your menstrual cycle will take some time to normalize.

There are women who go months without ovulating after the contraceptive is stopped. Eventually, menstruation will return, with no risk of infertility. You just need to be patient and the ovulatory cycle will reorganize naturally in 3 to 6 months.

However, it should be noted that any woman with more than 3 months of missed menstruation should seek advice from her gynecologist.

Post-contraceptive amenorrhea may occur in all forms of administration, including implants, injections, or tablets.


Being ill can be a cause of menstrual delay. It does not have to be a serious illness, like heart attack, tuberculosis or hepatitis. Common viruses such as flu, or simple infections, such as cystitis or tonsillitis, may be enough to disrupt your menstrual cycle, delaying your menstruation for a few days.

Some medications can also influence the hormonal cycle, deregulating your menstruation. Among the most common are:

  • Antipsychotics.
  • Glucocorticoids.
  • Antidepressants.
  • Chemotherapy.
  • Immunosuppressants.
  • Antihypertensives.

Note: In general, the use of antibiotics does not cause menstrual delay. What usually interferes with the menstrual cycle is the infection for which the antibiotic was prescribed.

5. Miscalculations

Women with irregular menstrual cycles may have some difficulty calculating the day the menstruation should begin. You may find that your period is late, when, in fact, it will just come 2 or 3 days later. Even women with a regular cycle may occasionally have menstruation a few days late, for no reason at all. Your uterus does not have a fixed calendar; it is not required to act like a perfect monthly clock.


Gaining or losing too much weight in a short time, are also causes of menstrual cycle deregulation. The fat cells in our body contribute to the production of estrogen, the female hormone responsible for the maturation of the eggs. Sudden changes in the amount of fat in the body alter estrogen levels acutely and may interfere with ovulation and, consequently, the date of menstruation.


This cause of missing period is a variation of the above situation. Overweight women possess a large mass of fatty tissue, which causes excessive estrogen production. This female hormone is required for ovulation, but, if it is in excess, it inhibits the release of the egg, causing anovulatory periods. Without ovulating, the woman does not menstruate.


The lack of fatty tissue also impairs the ovulatory cycle, as it reduces the female body’s ability to produce estrogen. Women who suffer from anorexia or extreme diets typically do not ovulate every month, presenting not only period delay, but also the risk of amenorrhea (more than 3 months of missing periods).


Women who exercise at high level also tend to have menstrual changes. We are not talking about that physically active woman, who goes to the gym frequently, but about triathletes, marathoners, competition swimmers, gymnasts and other professional athletes.

High caloric expenditure, intense workout stress, and low body fat rate appear to be responsible for changes in the menstrual cycle.


A thyroid that works poorly (hypothyroidism) or in excess (hyperthyroidism) can also alter the menstrual cycle.

In general, uncontrolled thyroid diseases can lead to amenorrhea, but even small changes in the blood levels of thyroid hormones can deregulate the cycle and cause menstrual delays.


If you have just had a baby and are breastfeeding, do not expect your menstruation to come in the next months. Breastfeeding does not cause a simple menstrual delay; it causes transient amenorrhea due to inhibition of ovulation, caused by the hormones that stimulate the production of breast milk. In general, the menstruation returns as soon as the weaning process begins.


Women with polycystic ovary syndrome (PCOS) often have irregular menstruation because they produce androgen (male hormones) in excess. Menstrual delays and complete absence of menstruation in a given month are very common in these cases. Women with PCOS  are usually overweight, which, as we have already seen, also contributes to irregular periods.


Menopause usually starts between the ages of 45 and 55. However, some women may have menopause before the age of 45. There are also those who have premature menopause, before the age of 40. One of the symptoms of imminent ovarian failure is dysregulation of the menstrual cycle and absence of ovulation in certain months. If you are over the age of 35, and your menstruation begins to frequent delay and often doesn’t come in certain months, see your gynecologist.

14. Menarche – Recent start of the menstrual cycle

If your menarche (first menstruation) has recently occurred, it is normal for your cycle to be irregular in the early years. Menstrual changes can occur throughout the first two years of menstruation because the female reproductive system is still in the maturing stage. Therefore, missed periods at this stage is extremely common.


Amenorrhea is different from menstrual delay. If you have not menstruated for three or more months, this can no longer be considered a simple menstrual delay

Some causes of amenorrhea have been cited in this text, but there are several others, including problems in the uterus, ovaries and even in the brain glands that control the production of sex hormones, such as the pituitary and hypothalamus.

Therefore, if you are not pregnant and your period has stopped coming, go to your gynecologist. There might be some underlying illness blocking your ability to ovulate.

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