Why Has My Period Suddenly Stopped? 9 Possible Causes

Have you noticed that your monthly menstrual cycle has suddenly stopped? For most women, periods tend to be irregular when they first begin menstruating during puberty. However, if you’ve missed three or more monthly cycles in a row, it’s time to see your doctor.

There are a number of potential reasons why your period may have halted, ranging from hormonal imbalances to significant weight fluctuations. Read on to learn about 9 common causes of missed periods and when you should seek medical evaluation.

1. Hormonal Imbalances

Hormones play a critical role in regulating the menstrual cycle. Imbalances in key hormones can disrupt the cycle and lead to paused periods, known medically as secondary amenorrhea.

Some examples of hormonal disorders that may cause amenorrhea include:

  • Polycystic Ovary Syndrome (PCOS): PCOS leads to a hormonal imbalance of elevated male hormones and insulin resistance. The ovaries may fail to regularly release eggs. Up to 80% of women with PCOS have infrequent, absent, or irregular periods.

  • Thyroid disorders: Both overactive (hyperthyroidism) and underactive (hypothyroidism) thyroid can impact menstrual cycles. Thyroid hormones help control ovulation.

  • Tumor on the pituitary gland: The pituitary gland in the brain makes hormones that signal the ovaries to produce estrogen and progesterone. Tumors may disrupt proper signaling.

  • Premature ovarian failure or early menopause: This refers to menopause occurring before age 40. Declining estrogen levels cause periods to stop. About 1% of women experience early menopause.

2. Weight Changes

Being significantly over- or underweight can affect the hormones that regulate menstruation.

  • Women who are underweight, with body weight more than 10% below normal, may experience amenorrhea due to low leptin levels. Leptin is the hormone made by fat cells that helps control appetite and signals the reproductive system. Too little body fat disrupts ovulation and periods.

  • On the flip side, being overweight or obese can also lead to irregular, absent, or infrequent periods. This is related to higher estrogen levels from excess fat as well as insulin resistance. Obesity is behind 30% of amenorrhea cases. Losing just 5% of body weight can help overweight women start ovulating and menstruating again.

3. Medications

A number of prescription and over-the-counter medications are linked to causing secondary amenorrhea. These include:

  • Antipsychotics and antidepressants: Drugs like risperidone, lithium, fluoxetine may affect prolactin and other hormone levels.

  • Cancer chemotherapy: Powerful chemotherapy medications damage ovarian function and egg production. Periods often stop during treatment.

  • Birth control pills or shots: Some oral contraceptives and injections like Depo-Provera cause lighter, less frequent, or no periods. This effect is temporary and periods return after stopping the medication.

  • Blood pressure medications: Drugs like angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers may alter menstrual cycles in some women.

  • Allergy and asthma medications: Antihistamines like loratadine (Claritin) have anti-estrogenic effects that can influence periods. Corticosteroids like prednisone also impact hormone levels.

Always review medications with your doctor if you experience sudden amenorrhea after starting a new prescription or over-the-counter drug. A switch to an alternative may be recommended.

4. Stress

High stress levels take a toll on the intricate hormonal choreography involved in regulating ovulation and menses. Stress primarily impacts a part of the brain called the hypothalamus which helps kickstart the menstrual cycle each month.

Women who have experienced major stressful life events, such as the death of a loved one, divorce, job loss, abuse, or traumatic accidents, are more prone to missing periods. High levels of physical stress from intense athletic training can also lead to functional hypothalamic amenorrhea. This “athletic triad” involves a combination of low body fat, stress, and high energy expenditure that disrupts menstruation.

Making time for regular relaxation, getting therapy if needed, and finding healthy coping mechanisms for chronic stress can help restore normal cycles.

5. Uterine Causes

Structural problems in the uterus itself rarely result in amenorrhea. But conditions like:

  • Asherman’s syndrome: Scarring or adhesions in the uterus, usually after surgery like a D&C

  • Endometrial tuberculosis: A rare infection of the uterine lining

can both lead to buildup of scar tissue. This may obstruct the uterus or prevent it from growing normally during the menstrual cycle, leading to missed periods.

6. Breastfeeding

It’s common for women not to get their periods back for several months after giving birth, especially if breastfeeding.

The high levels of the hormone prolactin while nursing help stimulate milk production while suppressing ovulation. As babies start eating more solid food and breastfeeding less often, prolactin levels drop back down allowing ovulation and menstruation to resume.

7. Birth Control Methods

Some contraceptive methods cause women to stop getting monthly periods altogether. These include:

  • Hormonal IUDs: Intrauterine devices (IUDs) like Mirena release the hormone progestin. This thickens cervical mucus to prevent pregnancy. Thinner uterine lining also lightens or stops periods.

  • Implants: Contraceptive rods like Nexplanon secrete progestin to inhibit ovulation. About 1 in 5 women using progestin implants experience lighter, less frequent, or no periods after the first year.

  • Combined hormonal contraceptives: Birth control pills, patches, and vaginal rings contain estrogen and progestin. These can lead to absence of withdrawal bleeding during the placebo week for some women.

  • Progestin-only pill: The "mini-pill" works by thickening cervical mucus and thinning the uterine lining. About 50% of women using it experience little to no bleeding.

Discuss your birth control method with your healthcare provider if you'd prefer to have a monthly period or are concerned about sudden amenorrhea. Some loss of menstruation is an expected side effect, but make sure there are no other underlying medical reasons.

8. Menopause

As women approach menopause, usually in their late 40s to early 50s, the ovaries start producing less of the key hormones estrogen and progesterone. These fluctuating and declining hormone levels cause changes in the menstrual cycle including skipped periods.

Perimenopause is the transition period leading up to menopause when periods become irregular but haven't stopped completely. During perimenopause, cycles may be longer or shorter, lighter or heavier, and become sporadic.

Amenorrhea during perimenopause is normal and to be expected as part of the process. But premature menopause before age 40 warrants a medical evaluation.

9. Eating Disorders

Women suffering from eating disorders like anorexia nervosa and bulimia often experience severe malnutrition, very low body weight, and critical hormonal and electrolyte imbalances. This can lead to functional hypothalamic amenorrhea and absent periods.

Resuming normal eating habits is the first step in correcting the hormonal dysfunction and getting regular periods back for those recovering from disordered eating. Seeking professional treatment improves outcomes.

Other Symptoms to Watch Out For

While a missed period is the hallmark of amenorrhea, other symptoms can also indicate an underlying problem:

  • Milky discharge from breasts

  • Excessive facial or body hair growth

  • Hair loss or thinning

  • Headaches

  • Vision changes

  • Acne flare-ups

  • Hot flashes and night sweats

  • Vaginal dryness

  • Breast size changes

  • Pelvic pain

Monitoring for these associated symptoms helps clue your doctor into potential causes like thyroid disorders, hormonal imbalances, or early menopause.

When to See a Doctor

  • See your doctor if you've missed 3 or more periods in a row.

  • Get evaluated if you have any symptoms of hormonal imbalance like unusual hair growth, breast discharge, headaches, or vision changes along with amenorrhea.

  • Make an appointment if you have severe pelvic pain along with missed periods.

  • See your doctor if you have a negative home pregnancy test but no period.

  • Women over age 45 who suddenly stop getting their period should still get checked out to rule out problems besides perimenopause.

  • Seek emergency care if you experience heavy vaginal bleeding after prolonged amenorrhea.

Don’t assume that a late or skipped period is “no big deal”, especially if it’s accompanied by other symptoms or you’re not sure of the cause. Your doctor can help determine if amenorrhea is due to an underlying medical condition needing treatment.

The Takeaway

Missed or irregular periods happen from time to time and are usually not a major worry. But if you’ve noticed your monthly cycle suddenly stopped, take note. Tracking your periods and being aware of changes is important.

From hormones to medications to menopause, there are quite a few reasons why your period may have taken an unexpected pause. Don’t hesitate to see your doctor for an evaluation if you’ve missed three or more cycles or have any troubling symptoms. Getting to the root cause can help you get your cycle regularity back on track.