Common Reasons Why Your Period Is Lighter Than Usual

A period that seems light is usually not a cause for concern. However, it can sometimes be a sign of hormonal shifts or certain medical conditions. Most people experience a natural fluctuation in their menstrual periods from time to time. It can happen with stress, weight loss or gain, or changes in birth control.

It can also be a sign of pregnancy. Spotting in early pregnancy is often caused by implantation bleeding, which may just seem like a light period. Lighter than normal period blood can be pink, red, or brownish. It may or may not involve cramps and period pain.

This article explores the different reasons for why your period may be lighter than usual. It also explains common causes for lighter periods and when to call a healthcare provider.

Pregnancy

Pregnancy is the most likely cause of a change in menstrual cycles for those who are sexually active. Some people (up to 25%) may experience spotting or breakthrough bleeding in early pregnancy.

Implantation bleeding is often mistaken for a light period. Implantation is when a fertilized egg attaches to the uterine wall.

Implantation bleeding:

• Occurs a few days before your period would normally appear
• Can vary in shade from light pinkish-red to bright red or a reddish-brown to dark brown
• May or may not be accompanied by cramps or pain
• Does not always occur or may not be noticeable

Cervical bleeding is another potential cause of light bleeding during pregnancy. During pregnancy, the cervix is more sensitive and may bleed after intercourse.

If you know you are pregnant, talk to an ob/gyn or midwife about any vaginal bleeding. Light spotting with pink or brown blood can be normal throughout pregnancy. Heavier bleeding, bright red or dark blood, and blood accompanied by cramping or pain can indicate a problem and should be seen promptly.

If you suspect that you're pregnant due to a lighter-than-normal period, take a pregnancy test, especially if you have not been using birth control. If you test negative, you can wait a week and test again or wait to see if your period comes next month.

Lactation

People who are nursing have high levels of prolactin in their bodies. It's a hormone produced by the pituitary gland to stimulate breast milk production.

Prolactin also plays a role in regulating the menstrual cycle. Your periods may be lighter or shorter when nursing a baby, but they typically return to normal once you've stopped. Sometimes, a prolactin level may be related to a medication or a medical condition and needs to be evaluated by a healthcare provider.

Weight Loss or Gain

If you have suddenly gained or lost a lot of weight, you may see a change in your menstrual cycle. If you're underweight, the loss in fat can cause you to stop ovulating or releasing an egg every month. Exercising too much can also affect your periods because it changes the hormone levels in your body.

Stress

Emotional stress, such as the loss of a loved one, or major life stressors in work or your home life can take a toll on your body and affect your menstrual cycle.

Birth Control

Going on hormonal birth control can also cause a change in your period. It is not uncommon for people to experience lighter-than-usual periods and shorter periods while on a birth control pill or after getting a hormonal IUD, such as Mirena.

If a change in your period bothers you, you can use a birth control method that closely mimics your normal periods. Hormone-free options that should not or are less likely to affect your periods are also available, including internal and external condoms, a non-hormonal IUD device, and spermicidal foams.

Be sure to ask a healthcare provider for advice on the method that is best for you.

Age

If you are getting older, your periods may change, in some cases becoming lighter. This could mean that you are pre-menopausal. This does not necessarily mean you are no longer fertile, just that you are less likely to get pregnant. If you do not want to get pregnant, you should still use birth control until menopause.

Medical Conditions

Certain medical conditions can lead to lighter periods. Your healthcare provider can help you determine if any of these conditions are causing your symptoms.

Thyroid Disorder

Sometimes, your period may be light due to a thyroid disorder. The thyroid gland (and other endocrine system glands) help to regulate the menstrual cycle and can contribute to changes.

Polycystic Ovary Syndrome

People diagnosed with polycystic ovary syndrome (PCOS) also may experience lighter than normal periods due to the hormone-related disruptions PCOS typically has on the menstrual cycle.

Asherman's Syndrome

There are other medical conditions, such as cervical stenosis or Asherman's syndrome (uterine scars), that may cause a lighter flow than expected, though cramping may still occur. Both are uncommon, but these conditions can cause menstrual blood to get trapped in the uterus.

Asherman's syndrome is most often caused by uterine scarring following a dilation and curettage procedure (D&C), in which tissues from the uterus are removed.

What Is Considered a Light Period Flow?

The amount considered a light period flow will differ from one person to another. That said, on average there are about two or three tablespoons of blood lost by a person on their period.

Some people may have lighter periods than the average, while others can have heavier periods. This can also change from one month to the next.

When to See a Healthcare Provider

One of the most important reasons to see a healthcare provider about a period that's light is the possibility that you may be pregnant. You may opt for an at-home test first.

If your periods are consistently light but didn't used to be, that's a change in your menstrual cycle that needs to be evaluated. You also should see a provider if you have symptoms including:

• Fever
• Pelvic pain
• Vaginal discharge that's different in color or odor
  

Summary

Your period can be lighter than normal due to natural reasons, such as stress or perimenopause. It can also be lighter because of the birth control you are using, particularly if you are taking hormonal birth control pills or using a hormonal IUD. If your period seems off and you're not sure why, let a healthcare provider know.

Tracking your period symptoms can help. Consider downloading a period tracker app on your smartphone, or simply taking notes about your period in your calendar. This way, if something is unusual about your period one month, you'll be more likely to notice.