Reasons for missed period and not pregnant

Some people’s periods arrive each month like clockwork. For others, periods are unpredictable and may come as a surprise. Sometimes, they don’t happen at all! This doesn’t necessarily mean you’re pregnant.

Missed or late periods may happen for a variety of reasons apart from pregnancy. Common causes of missed or irregular periods range from hormonal imbalances to medical issues. Let’s discuss the main reasons for a missed period and when it’s time to contact a health care provider. 

Is it normal to miss a period? 

There are several times in a person’s life when irregular periods are expected: when a person first starts having periods (puberty), during breastfeeding, and at the beginning of perimenopause (the transitional stage that precedes menopause). On average, most people get their periods every 28 days. But a healthy person’s menstrual cycle can last from 21 to 35 days. Apart from puberty, menopause, and pregnancy, a missed period may indicate a health issue.

Is it possible to miss a period for a month?

Yes, you may have a missed period for many reasons other than pregnancy. The reasons why you miss your period for a month may include stress, low body weight, obesity, polycystic ovary syndrome (PCOS), use of birth control, certain chronic diseases, early perimenopause, and thyroid issues. 

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No period for three months: Is this normal?

Not having your period for three months or more is known as secondary amenorrhea. This can happen for a variety of reasons. Natural causes of an absence of menstruation for three months include perimenopause, pregnancy, and breastfeeding. Certain lifestyle factors like stress and excessive exercise may also cause it. Furthermore, having either excessive or low body fat can also cause a missed period. Tumors on the pituitary gland or a hypoactive/hyperactive thyroid gland can also lead to hormonal imbalances and trigger secondary amenorrhea. Low levels of estrogen or high levels of testosterone can also result in a missed period. 

Genetic disorders such as Swyer syndrome and Turner syndrome result in a lack of menstruation without proper hormone replacement therapy. Some people experience a missed period because of medications such as antidepressants, antipsychotics, or chemotherapy drugs. You could also notice no period for three months or more if you have just stopped taking birth control pills. 

Physical issues like problems in your reproductive organs could also cause delayed or missed periods. 

How much of a delay in periods is normal?

You can calculate the length of your menstrual cycle by counting from the first day of one period to the first day of the next. Typically, menstrual cycles range from 21 to 35 days. If your periods are within this range, then there’s probably no cause for concern.

Causes of missed periods other than pregnancy 

Some of the causes of missed periods, besides pregnancy, are as follows:

• Stress: This is one of the most common reasons for a missed period. Stress can result in a hormonal imbalance and even affect the hypothalamus — the part of the brain that helps regulate your periods. Stress can also lead to weight loss or gain or other illnesses, all of which can affect your cycle. Stress can result from many factors such as traveling, professional and relationship issues, emotional problems, financial concerns, etc. 
• Low body weight: Low body weight is another potential reason for a missed period. People with eating disorders like bulimia or anorexia nervosa may experience an absence of menstruation. If your body weight is too low, you might stop ovulating because of hormonal changes. Athletes who participate in some forms of exercise, like marathons, may also experience missed periods. 
• Obesity: Similarly to low body weight, obesity can also result in hormonal changes, leading to an absence of menstruation. 
• Polycystic ovary syndrome (PCOS): PCOS is a condition in which your body produces more of the male hormone androgen. Due to this hormonal imbalance, ovulation stops or becomes irregular, and arrested follicles (cysts) form in the ovaries. This results in a missed period. Together with androgens, other hormones such as insulin can also be disrupted by PCOS. 
• Birth control: Stopping or starting birth control can produce changes in your menstrual cycle. Birth control contains the hormones progesterone and estrogen, which prevent the ovaries from releasing eggs. Within three months, your period will likely become regular after you stop or start taking birth control pills. Other kinds of hormonal contraceptives that are injected or implanted can also cause missed periods. 
• Chronic diseases: Certain chronic illnesses such as celiac disease and diabetes can also affect your period. Blood sugar changes can affect hormones, and poorly controlled diabetes can lead to irregular periods. Celiac disease causes inflammation in the small intestine and prevents the body from absorbing vital nutrients, contributing to missed or late periods. 
• Thyroid issues: An underactive or overactive thyroid gland can also cause irregular periods. The thyroid gland regulates the metabolism of your body, so thyroid issues can also affect hormone levels, prompting you to miss a period. 
• Early perimenopause: For most, menopause begins between the ages of 45 and 55. If symptoms of menopause start before the age of 40, it’s considered early perimenopause. Early perimenopause means that the supply of your eggs is declining. This can result in a missed period and eventually the end of menstruation. 

Should I contact my health care provider after a missed period?

It might be a good idea to ask your health care provider about a missed period or irregular periods, especially if your periods are usually regular. A health care provider can help you figure out the reason for your missed period and suggest appropriate treatment options. 

Visit your doctor if you notice the following symptoms:

• You’ve missed your period three or more times in a year.
• You get a period more frequently than every 21 days.
• You get a period less frequently than every 35 days.
• Bleeding lasts for more than seven days.
• Bleeding is heavier than normal.
• You have severe pain during your period.
• You have a fever.
• You have postmenopausal bleeding (bleeding after you have entered menopause and not had a period for one year).

A late or missed period can occur for multiple reasons apart from pregnancy. Potential causes range from hormonal imbalances to more serious medical issues. Many people experience irregular periods during puberty, at the beginning of perimenopause, and during pregnancy. 

A missed period can sometimes indicate a health issue. Some causes of a missed period other than pregnancy include stress, low body weight, obesity, polycystic ovary syndrome, use of birth control, chronic diseases, thyroid issues, and early perimenopause. 

If you’re experiencing a change in the pattern of your regular periods, make sure to contact your health care provider. 

Updated on February 24, 2021

NHS Choices, NHS, www.nhs.uk/conditions/stopped-or-missed-periods/.

“Amenorrhea.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 25 July 2019, www.mayoclinic.org/diseases-conditions/amenorrhea/symptoms-causes/syc-20369299.

“Absent Menstrual Periods - Primary: MedlinePlus Medical Encyclopedia.” MedlinePlus, U.S. National Library of Medicine, medlineplus.gov/ency/article/001218.htm.

Klein, David A., and Merrily A. Poth. “Amenorrhea: An Approach to Diagnosis and Management.” American Family Physician, 1 June 2013, www.aafp.org/afp/2013/0601/p781.html.