Many people who miss a period will take a test to check for pregnancy. If the pregnancy test is negative, a variety of conditions and factors may be responsible for the lack of menstruation.
In this article, we explain how the menstrual cycle works and provide some possible causes of a missed period other than pregnancy. We also cover how to make a home pregnancy test as accurate as possible and when to see a doctor.
The ovaries release an egg in a process called ovulation, which occurs approximately every 28 days. If no sperm fertilizes the egg, a person's period will usually start about 14 days later.
While a missed period is one of the first signs of pregnancy, there are a variety of other reasons why it can occur.
Amenorrhea usually happens when the ovaries stop making enough of the female hormone estrogen. A range of factors, including those below, can cause a lack of estrogen.
1. Weight changes
The rapid gain or loss of a significant amount of weight can lead to hormonal imbalances. These imbalances can cause a person to miss periods initially, but they tend to resolve over time.
Long-term or intense stress can affect the part of the brain that controls the reproductive hormones. This can cause ovulation and periods to stop.
Once the cause of the stress goes or the person learns coping strategies to manage it, their regular cycle may return.
3. Excessive exercise
Excessive exercise can cause missed periods, particularly for people with low body weight or very little body fat. Missing periods due to excessive exercise is called exercise-associated amenorrhea.
4. Producing too much prolactin
Prolactin is a hormone that the body usually makes during breastfeeding. It can halt menstruation and is the reason why most breastfeeding women do not have periods.
In people who are not breastfeeding, a milky discharge from the nipples can signify that the body is making an abnormally high amount of prolactin. Doctors can treat excessive prolactin production with medication.
5. Thyroid problems
The thyroid is a gland that produces hormones to control the body's metabolism.
Hypothyroidism, or an underactive thyroid, is a condition in which the thyroid does not produce enough of these hormones. Hyperthyroidism, or an overactive thyroid, results in the levels of thyroid hormones in the body being too high.
Both conditions can affect the frequency of periods. Other signs to look out for include:
- fatigue or extreme tiredness over a prolonged period
- hair loss
- unexplained weight gain or loss
- always feeling cold or being warm all the time
Doctors can usually diagnose thyroid problems using a simple blood test.
6. Polycystic ovary syndrome (PCOS)
People with PCOS have a hormonal imbalance that can affect their overall health and appearance in addition to causing ovarian cysts.
Signs of PCOS include:
- irregular periods or no periods
- very light, very heavy, or unpredictable bleeding during periods
- skin conditions, such as acne, dark patches, or skin tags
- being overweight or obese
- thinning hair
- sleep apnea
- difficulty getting pregnant
- excess hair on the face, back, or thighs
7. Eating disorders
Eating disorders, particularly anorexia, can cause periods to stop. This happens when a person's body fat becomes too low for ovulation to occur.
People enter menopause when they have not had a period for at least 12 months. The average age of people entering menopause in the United States is 52 years old. However, the transition to menopause, known as perimenopause, may cause symptoms that begin at a younger age.
The symptoms of perimenopause include:
- irregular periods
- heavier or lighter periods
- hot flashes
- problems sleeping
- mood swings or irritability
- vaginal dryness
- less interest in sex
Home pregnancy tests can sometimes give a false negative result, indicating that someone is not pregnant when they are.
The accuracy of a home pregnancy test varies depending on how and when a person takes it. Some of the reasons a test may give a false negative result include:
- Taking a test too soon: Home pregnancy tests look for the presence of human chorionic gonadotropin (hCG) in urine. Although some tests can detect hCG from the first day of a missed period, they are generally more accurate later on.
- Low hormones: Tests are usually more precise first thing in the morning because the urine is less diluted at this time and this makes hCG easier to detect.
People who miss more than three periods in a row and have a negative pregnancy test result should see a doctor.
A person may miss a period as a result of several causes, including specific medical conditions, so it is essential to get a proper diagnosis.
To ensure that a home pregnancy test is accurate, people should follow the instructions on the packaging and wait until at least a week after the first day of the missed period before taking the test.