Why Is My Period Late? (10 Reasons and When to See Your Doctor)



Your period is late but you’re sure you’re not pregnant? Periods can be late for many different reasons other than pregnancy. This is mostly due to changes in your daily habits or hormonal imbalance.
It’s normal for your period to be irregular in two situations. During puberty, when your body is going through major hormonal changes, and during menopause when the ovaries stop producing as many hormones responsible for ovulation.

1. Polycystic Ovarian Syndrome

PCOS is s syndrome that causes your body to produce more testosterone, a male androgen hormone. In turn, this causes a hormonal imbalance resulting in cysts forming on ovaries, making the menstrual cycle irregular.

The exact cause of PCOS is unknown. The treatment is mostly focused on relieving the symptoms. Additionally, your doctor can recommend weight loss to reduce the risk of long-term complications such as type 2 diabetes and heart disease.

2. Thyroid conditions

Your thyroid produces many hormones that regulate your body’s functions. Most importantly, how quickly you burn calories and how rapidly your heart beats. Thyroid disorders can produce either too much or too little of it.

Your thyroid helps to regulate the cycle of your menstruation. Some conditions may make your cycles very light, hard, or irregular. A thyroid disorder, a condition called amenorrhea, can also cause the cycles to stop for several months or longer.

3. Sleep Schedule

Your body counts on your natural sleep cycle to secrete different hormones responsible for all bodily functions. A regular sleep schedule often keeps the biological schedule consistent.

But when the sleep pattern is thrown off, hormone secretion is not as consistent and normal as it normally is, which in turn affects reproductive hormone secretion. If you’re not sleeping enough, your body cannot secrete the hormones responsible for your menstrual cycle, which in turn causes your period to be late.

4. Low body weight

Excessively low body weight interrupts many hormonal processes throughout the body, possibly stopping ovulation. This weight is usually defined as about 10 percent below average weight.

During puberty, the body starts producing more sex hormones when your body fat content increases. In women of low body weight, the fat content is also low, possibly triggering the loss of the period. Women who have an eating disorder, such as anorexia or bulimia can also lose periods due to this hormonal imbalance.

5. Anemia and iron deficiency

Anemia is defined as the low content of red blood cells, responsible for carrying oxygen to every cell of your body. It is the most common blood condition in the U.S, affecting almost 6% of the population.

If a woman is iron deficient or faces issues with proper absorption of iron, it may impair the flow of blood in the body and, as a result, make you skip periods or have them fairly late. Treatment focuses on determining the reason behind the low iron levels and supplementation.

6. Workout intensity

Even though exercising is extremely beneficial for your body, intense workouts can interrupt the balance of the hypothalamic-pituitary-ovarian axis in some people. Hypothalamus is a part of your brain responsible for many hormones in your body, including the secretion of your reproductive hormones.

Vigorous exercise often combines with a low calorie intake, places substantial stress on your body, making the hypothalamus stop stimulating the ovaries, resulting in a late or missed period.

7.  Breastfeeding

If you’re breastfeeding, it’s normal for your period not to return even a few months after giving birth. This is due to the effect of prolactin, a hormone responsible for milk production, stopping ovulation and causing your period to be late.

The longer you nurse, the longer your prolactin levels will be high, postponing the ovulation. Some women may not even get their first period up to a year after giving birth.

8. Medications

Some medications can interfere with your regular menstrual cycle, causing your period to be late or missing. Some of the most common medications that can cause this are Aspirin or similar blood-clotting medications, antidepressants, as well as thyroid medications.

Always make sure to discuss your medications with your healthcare provider to assess the best options if you’re experiencing a late period.

9. Birth Control

Some birth control options can cause your period to be late, or even missing for months. Birth control pills often make your periods lighter, less painful and shorter. If you’re taking a progesterone-only pill, also known as a “mini-pill”, your cycles can be irregular in the beginning.

This can also happen if you’ve stopped using birth control pills as the body can take up to a year to start its natural menstrual cycle.

10. Stress

The human body has evolved using its fight-or-flight instinct. While it formerly protected from danger and predators, today it is mostly activated during stressful situations. When your body determines it is in a stressful situation, your brain tells your endocrine system to flood your body with hormones that switch on your fight-or-flight mode.

This causes it to shut down any function that is not essential for escaping the danger, including the reproductive system.

If you’re constantly under a lot of stress, your body can stay in a fight-or-flight mode temporarily stopping the ovulation. This, in turn, causes your period to be late. The best way to combat stress is through meditation that helps you transition from a fight-or-flight mode to normal.

When to see your doctor

If you’re experiencing any of these symptoms, consult with your doctor or OB/GYN:

  • Your period is late more than 30 days
  • You missed more than 1 period
  • You’re experiencing unusual bleeding between your periods
  • You’re feeling lightheaded, dizzy, or fatigued
  • Your periods suddenly change, become much heavier, or are more erratic


Your period is generally considered to be late if it is more than 30 days after the date it was expected to start. There are many reasons why your period can be late, ranging from the medications you take, the intensity of your workouts, or over-exposure to stress. Making simple changes to your daily routine can help your menstrual cycle get back on track!