The length of your period can fluctuate depending on many different factors. If your period suddenly becomes much shorter, though, it’s normal to be concerned.

While it could be an early sign of pregnancy, there are many other possible causes, including lifestyle factors, birth control, or a medical condition.

Read on to learn more about what could cause your period to only last a day or two.

A normal menstrual cycle happens about once every 28 days, but this often varies. Some women have periods every 21 days, while others have periods that are 35 days apart.

When it comes to periods, every woman is different. Most women have periods that last around three to five days each month. But a period that lasts only two days, or goes on for seven days, is also considered normal.

If your period typically lasts several days and suddenly becomes much shorter, it could be due to a variety of causes.

Pregnancy may be the reason for a “period” that lasts only one or two days.

When a fertilized egg attaches to the lining of the uterus, implantation bleeding can happen.

This type of bleeding is usually lighter than a regular period. It most often lasts about 24 to 48 hours. It’s typically light pink to dark brown in color.

Implantation bleeding usually occurs about 10 to 14 days after conception. Not all pregnant women will experience it, though. According to the American College of Obstetricians and Gynecologists, implantation bleeding only happens in about 15 to 25 percent of pregnancies.

An ectopic pregnancy happens when a fertilized egg attaches to the fallopian tubes, ovary, or cervix instead of the uterus. It’s commonly called a tubal pregnancy.

One of the first signs of an ectopic pregnancy is vaginal bleeding along with pelvic pain.

If a fertilized egg keeps growing in the fallopian tube, it can cause the tube to rupture. That can lead to heavy bleeding inside the abdomen.

Seek medical help right away if you experience symptoms of an ectopic pregnancy, such as:

  • severe abdominal or pelvic pain, usually on one side
  • fainting or dizziness
  • abnormal vaginal bleeding
  • rectal pressure

A miscarriage can cause bleeding that may be mistaken for a period. Many women may be unaware they’re having a miscarriage since they might not have known they were pregnant to begin with.

The bleeding may be a light spotting or a heavy flow. The length and amount of bleeding will depend on the length of the pregnancy.

Other symptoms of miscarriage include:

  • cramping
  • abdominal or pelvic pain
  • back pain

Breastfeeding can cause a delayed, lighter, or shortened period.

Prolactin, a hormone that helps make breast milk, also prevents menstruation from occurring.

Most women who breastfeed will resume their periods around 9 to 18 months after their baby is born.

Hormonal birth control pills or shots as well as intrauterine devices (IUDs) can cause shorter and lighter menstrual cycles.

The hormones in birth control pills can thin out the lining of the uterus. This can lighten and shorten your period. According to the Cleveland Clinic, women who take progestin-only pills may bleed between their periods.

Other medicines that may affect the frequency, length, or flow of your period include:

  • blood thinners
  • antipsychotics or antidepressants
  • steroids
  • herbs, such as ginseng
  • tamoxifen (a medicine used to treat certain types of breast cancer)

A lot of different lifestyle factors can affect the duration of your period, including changes to your daily routine.

Let’s take a closer look at some of the most common lifestyle changes that can cause changes to your period.

Stress

High levels of stress can affect your hormones. This, in turn, can affect your menstrual cycle.

If you experience severe stress, you might have irregular, shorter, or lighter periods than normal. Or you may not have a period at all.

Your periods will most likely return to normal once your stress levels go back down.

Significant weight loss

Losing a lot of weight may lead to irregular periods. Eating disorders, like anorexia nervosa or bulimia nervosa, can cause periods to stop altogether.

Excessive exercise

An extreme amount of physical activity can cause irregular periods or the absence of a period.

If you don’t balance the amount of energy you burn with adequate nutrition, your body won’t have enough energy to keep all your systems working. So, it will start to shift energy away from some functions, like reproduction.

As a result, the hypothalamus, a region in your brain, may slow down or stop the release of the hormones that control ovulation.

Some types of medical conditions may affect your monthly cycle, causing a shorter period than normal.

Thyroid disease

Thyroid disease causes your body to produce too much or too little thyroid hormone. This hormone plays a vital role in your menstrual cycle.

When your body doesn’t produce the right amount of this hormone, your periods can become irregular and sometimes shorter than usual.

Symptoms of thyroid disease can vary, depending on what the type of disorder you have. But the most common symptoms include:

  • weight loss or gain
  • trouble sleeping, or feeling very fatigued
  • a faster or slower heart rate than normal

Polycystic ovary syndrome (PCOS)

With PCOS, your body produces more male hormones than normal. This type of hormonal imbalance can stop ovulation from happening.

As a result, you may have a much lighter and shorter period, or no period at all. Other symptoms of PCOS can include:

  • excessive facial hair
  • fatigue
  • a deeper voice
  • mood swings
  • infertility

Pelvic inflammatory disease (PID)

PID is a type of infection that happens when bacteria enter the vagina and spread to the uterus and upper genital tract. This infection is usually transmitted through sexual contact.

PID may cause irregular periods, but they’re typically heavier, longer, or more painful.

Other conditions

Less common conditions that may cause irregular or shorter periods include:

Young women going through puberty may have irregular periods for the first few years after they start menstruating.

Another time when periods may become irregular is during perimenopause. This occurs quite a few years before menopause.

According to the Cleveland Clinic, women can enter perimenopause 8 to 10 years ahead of menopause, meaning it could happen in your 30s or 40s.

During perimenopause, estrogen levels start to drop. This can cause irregular periods.

Bleeding for only a day or two may be a sign of pregnancy, but there are many other possible causes, too.

If you’re concerned about your shorter than usual period, make an appointment to see your doctor. They can help you figure out what’s triggering the change and start treatment, if needed.