Top 8 Causes Of Blood Clots During Periods – Woman’s Health

I remember the first time I noticed a blood clot during my period. I was in my teens, and it scared the daylights out of me. I thought something was seriously wrong. Over the years, I’ve learned that these are a completely normal part of menstruation, and understanding the reasons behind them can be both enlightening and reassuring.

So, whether you’ve experienced this yourself or you’re just curious, here are 8 causes of blood clots during periods.

1. Normal Menstrual Flow

The menstrual cycle is a complex process, and sometimes, blood clots are just a part of a woman’s regular period.

Shedding of the Uterine Lining

Every month, the uterus prepares itself for a potential pregnancy by thickening its lining. If no pregnancy occurs, this lining is shed, leading to menstruation. During heavy flow days, the blood can pool in the uterus before being expelled, leading to clot formation.

Speed of Menstrual Flow

The speed at which menstrual blood is expelled can also influence clot formation. When the flow is heavy and rapid, the anticoagulants produced by the body might not get enough time to break down the blood, resulting in clots.

For those wondering about the varied shades of menstrual blood, including the reasons behind the appearance of brown blood, you can delve deeper into the topic here.

2. Hormonal Imbalances

Hormones play a pivotal role in regulating the menstrual cycle. Any imbalance can lead to changes in the menstrual flow, including the formation of clots.

Estrogen and Progesterone Levels

Estrogen and progesterone are the primary hormones responsible for regulating the menstrual cycle. An imbalance, especially an excess of estrogen, can cause the uterine lining to thicken more than usual.

When this thickened lining is shed, it can lead to heavier periods and increased clotting.

Thyroid Hormone Imbalances

The thyroid gland produces hormones that influence menstrual flow. An underactive or overactive thyroid can lead to heavier or lighter periods, respectively. In cases of hypothyroidism (underactive thyroid), cycles can be heavier, increasing the chances of clot formation.

3. Uterine-Related Conditions


The uterus is the epicenter of the menstrual cycle. Conditions affecting the uterus can directly influence the presence of blood clots.

Fibroids and Polyps

Uterine fibroids are non-cancerous growths in the uterus, while polyps are small, benign growths on the uterine lining. Both can cause disruptions in the menstrual flow. They can lead to heavier periods, which in turn can result in the formation of larger clots.


Endometriosis is a condition where tissue similar to the uterine lining grows outside the uterus. This can lead to painful cycles and heavy menstrual flow. Excessive bleeding can cause the formation of clots, especially during the initial days of the period.

4. Inherited Clotting Disorders

Genetics can play a role in how our bodies function. Some women might inherit disorders that make them more prone to clotting, which can manifest during menstruation.

Von Willebrand Disease (VWD)

Von Willebrand Disease is a hereditary bleeding disorder where the blood doesn’t clot properly. Women with VWD often experience heavy menstrual bleeding, which can lead to the formation of larger clots.

It’s essential to consult a doctor if you suspect you have VWD, as it can impact other aspects of health as well.

Factor V Leiden Mutation

This genetic mutation increases the clotting tendency of blood. While it can lead to serious conditions like deep vein thrombosis, in the context of menstruation, it can cause the menstrual blood to clot more than usual, leading to noticeable clots.

5. Medications and Treatments

Sometimes, the medications or treatments we undergo for other health conditions can inadvertently affect our menstrual cycle, leading to clot formation.

Anticoagulant Medications

Ironically, while anticoagulants are meant to prevent blood clots, they can sometimes cause heavy menstrual bleeding, leading to clot formation. If you’re on anticoagulants and notice significant clotting, it’s crucial to discuss this with your healthcare provider.

Certain Cancer Treatments

Treatments like chemotherapy or pelvic radiation can lead to changes in menstrual flow. These treatments can cause the menstrual cycle to become irregular or lead to heavier bleeding, increasing the chances of clot formation.

6. Lifestyle Factors

Lifestyle Factors

Our daily habits and lifestyle choices can influence our health in various ways, including the nature of our menstrual flow.


Obesity can lead to hormonal imbalances, especially in estrogen levels. As discussed earlier, high estrogen levels can cause a thicker uterine lining, leading to heavier cycles and increased clotting.


Smoking affects blood circulation and can lead to various vascular issues. It can also influence the menstrual cycle, leading to heavier periods in some women, which can result in clot formation.

7. Pregnancy-Related Causes

pregnancy test

Pregnancy brings about a whirlwind of changes in a woman’s body. Sometimes, these changes can lead to clot formation during periods post-pregnancy.


A miscarriage can lead to heavy bleeding and the passing of tissue. This can sometimes be mistaken for large blood clots. It’s essential to consult a doctor if you suspect a miscarriage.

Postpartum Periods

The first few cycles after childbirth can be heavier than usual. This is because the body is shedding the extra lining that supports the pregnancy. This can lead to the formation of larger clots than one might be used to.

8. Other Underlying Health Conditions


Some health conditions, while not directly related to the reproductive system, can influence menstrual flow and clot formation.


Anemia, especially iron deficiency anemia, can lead to heavier periods. The body might try to compensate for the lack of red blood cells by shedding more of the uterine lining, leading to clot formation.

Liver Disease

The liver plays a crucial role in producing clotting factors and breaking down hormones like estrogen. Liver diseases can disrupt these processes, leading to hormonal imbalances and altered clotting, which can manifest as blood clots.

What to Do?

Track Your Menstrual Cycle

Noticing blood clots during your period can be concerning, especially if it’s a new experience for you. Here’s what you should do:

  • Stay Calm: First and foremost, don’t panic. Blood clots during periods, especially small ones, can be a normal part of menstruation for many women. They often occur because the body’s natural anticoagulants can’t keep up with a heavy flow.
  • Observe the Size and Frequency: Pay attention to the size of the clots. Small clots (about the size of a dime or smaller) are typically not a cause for concern. However, if you’re consistently passing larger clots (the size of a quarter or bigger), it might be indicative of a more significant issue.
  • Track Your Menstrual Cycle: Use a period tracking app or a journal to note the days you observe clots, their size, and any other unusual symptoms. This can be helpful information to share with a healthcare professional.
  • Maintain Good Hygiene: Change your sanitary products regularly, whether you’re using pads, tampons, or menstrual cups. Keeping the area clean can help prevent infections.
  • Consult a Healthcare Professional: If you’re concerned about the clots or if you notice other symptoms like excessive pain, very heavy bleeding, or prolonged periods, it’s essential to consult a gynecologist or primary care provider.
  • Consider Lifestyle Factors: Factors like obesity, smoking, and certain medications can influence menstrual flow and clotting. If you believe any lifestyle factors might be contributing, discuss these with your doctor.
  • Stay Informed: Educate yourself about menstruation and the various factors that can influence it. Understanding your body can help alleviate concerns and empower you to make informed decisions about your health.
  • Seek Support: Talk to friends, family, or support groups about your experience. Sharing and hearing others’ experiences can provide comfort and additional insights.


Can the size of the blood clot indicate a potential health issue?

Generally, small clots (about the size of a dime or smaller) are considered normal. However, if you’re consistently passing larger clots (the size of a quarter or bigger), it might be a sign of a more significant issue and should be discussed with a doctor.

Does using a menstrual cup or tampon influence the formation of these clots?

Menstrual cups and tampons collect or absorb menstrual flow, respectively. While they don’t directly cause clot formation, they might make clots more noticeable when they’re removed.

The flow’s pooling in a menstrual cup can sometimes lead to clotting, but this is not a direct result of using the cup.

Can dietary changes have an impact on this?

Diet can influence overall health and, indirectly, menstrual health. For instance, a diet rich in omega-3 fatty acids might help reduce menstrual cramps. However, there’s limited direct evidence to suggest that diet can influence blood clot formation.

Are teenagers more prone to blood clots during their periods?

Teenagers might experience irregular cycles and varied flow as their bodies adjust to the menstrual cycle. While they aren’t necessarily more prone to blood clots, they might notice them more as they become familiar with their cycle.

Over time, as their cycle regulates, the occurrence of clots might decrease.

Can stress be the cause?

Stress can have a myriad of effects on the body, including hormonal imbalances. While stress doesn’t directly cause blood clots during menstruation, it can lead to irregular periods or changes in menstrual flow, which might indirectly influence clot formation.

Final Thoughts

And there you have it! I hope this article sheds some light on a topic that many of us might find a bit intimidating or even alarming. Remember, our bodies are complex and fascinating, and sometimes, they just have their unique way of functioning.

If you ever feel concerned about what’s happening during your period, always reach out to a healthcare professional. But most importantly, always remember you’re not alone in this journey. We’re all learning, growing, and navigating the intricacies of our bodies together.