What‌ ‌to‌ ‌Know‌ ‌About‌ ‌Fibroids‌ ‌and‌ ‌Pregnancy‌ ‌

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Fibroids, also known as leiomyomas, are lumps of muscle tissue that grow in or on the uterus (womb). These growths are usually benign (not cancerous). While these growths are common, they may impact fertility and can sometimes cause pregnancy complications, such as miscarriage or preterm labor

Uterine fibroids affect 20% to 80% of people with a uterus by age 50. They are common during the childbearing years, with an estimated incidence of 20% to 40% between ages 25 and 44.

There are several types of uterine fibroids, and they can range in size. Most fibroids do not cause any symptoms, but some people with fibroids can have:

  • Heavy bleeding or painful periods
  • A feeling of fullness in the pelvic area (lower stomach area)
  • Enlargement of the lower abdomen
  • Frequent urination
  • Pain during sex
  • Lower back pain

Learn more about how fibroids can affect fertility, pregnancy, and the postpartum period.

Cropped shot of a pregnant woman suffering from back pain

Lumi Nola / Getty Images

Fibroids and Fertility

Many people with fibroids can get pregnant naturally. Treatment may not be necessary for conception. That said, fibroids are present in 5% to 10% of infertile people, and may be the sole cause of infertility in 1% to 2.4% of people.

While most people with fibroids don’t experience fertility issues, the location and size of certain fibroids may cause fertility complications in some people in the following ways:

  • A large fibroid that changes the shape and size of the uterus can hinder sperm transport and prevent fertilization.
  • Fibroids can cause fallopian tubes to be blocked, preventing the egg from reaching the uterus.
  • Submucosal fibroids (a type of fibroid that grows and bulges into the uterine cavity) have been observed to be linked to infertility, as they reduce the chances of implantation of the fertilized egg to the uterine lining.

While fibroids may cause infertility for some people, other reasons for infertility are more common. If you’re having trouble conceiving, your doctor may explore other possible causes before placing the blame on fibroids.

Are Fibroids Hereditary?

Researchers think that several factors play a role in the development of fibroids. These include:

Having a family member with fibroids increases your risk. If your mother had fibroids, your risk of having them is about three times higher than average.

Fibroids and Gestation

While there is a large amount of research on fibroids in nonpregnant people, data is limited on how fibroids can affect pregnancy.

The majority of fibroids do not change their size during pregnancy, but one-third may grow in the first trimester. Fibroid enlargement may be influenced by estrogen, and estrogen levels rise during pregnancy, which leads to growth.

Having a few small fibroids is rarely cause for concern. However, depending on the location of your fibroids, how many you have, and their size, your doctor will monitor for certain situations that can cause problems during pregnancy.

Do Fibroids Shrink During Pregnancy?

Fibroids may also shrink in pregnancy as their blood flow is redirected to the fetus instead. In a 2010 study, researchers found that 79% of fibroids that were present before a pregnancy decreased in size after delivery.

Risks

Although many pregnant people have a normal pregnancy despite fibroids, around 10% to 30% of pregnant people with fibroids develop pregnancy-related complications. These include:

  • Pain: This is the most common symptom associated with the presence of fibroids in pregnant people.
  • Miscarriage: Research shows twice the risk of spontaneous miscarriage (14%) in pregnant people with fibroids, compared with those without fibroids (7.6%).
  • Bleeding: Studies show a greater risk of bleeding (60%) in early pregnancy if the placenta is implanted close to the fibroid, compared with when there is no contact between the two (9%).
  • Abnormal placenta: Fibroids have been associated with placenta previa (implantation of the placenta over the cervix) and placental abruption (premature separation of the placenta from the uterus).
  • Preterm labor: Pregnant people with uterine fibroids during pregnancy are almost twice as likely to undergo premature delivery, compared with those without fibroids.
  • Poor contracting: Disruption of normal uterine tissue from fibroids may result in weak contractions. This makes it difficult to reach complete cervical dilation when in labor.
  • Cesarean section: Having fibroids has been linked to an almost fourfold higher chance of having a cesarean section delivery, compared with those without fibroids.
  • Postpartum hemorrhage: Poor contracting can also lead to bleeding after delivery. If the uterus can't contract, uterine blood vessels that fed the placenta might continue to bleed.

When to Call a Doctor

Postpartum hemorrhage is a medical emergency and usually occurs within 24 to 48 hours after delivery. Call your doctor immediately if you experience heavy vaginal bleeding after labor.

Treatment

In nonpregnant people, treatment for fibroids includes prescription painkillers, hormonal treatments, and surgery. During pregnancy, treatment for uterine fibroids is limited because of the risk to the fetus.

For some pregnant people, fibroids can be a constant source of discomfort during pregnancy. Since surgical treatments should be avoided, the following methods can help bring relief and manage symptoms:

  • Rest and hydration: Bed rest and staying well hydrated can help bring relief from fibroid pain.  
  • Diet: The incidence of uterine fibroids has been shown to be greater in populations who consume more red meats, refined flour, alcohol, and sugary or overly salty foods. A diet with oily fish, green vegetables, citrus fruits, soybeans, and broad beans is recommended for those with fibroids.
  • Anti-inflammatory drugs: While nonsteroidal painkillers can be used to manage fibroid pain, always consult your doctor before using them, as they can have an adverse effect on the pregnancy in the third trimester.

Myomectomy During Pregnancy

There is currently a lack of large, randomized, and controlled studies on the safety and efficacy of myomectomies (surgery to remove fibroids) during pregnancy.

Myomectomy during pregnancy may be useful only in certain specific instances, such as early in pregnancy and when fibroids are large, growing rapidly, and causing recurrent pain. However, the risk of pregnancy complications including miscarriage or fetal loss is of paramount concern.

Concerning Symptoms

If you experience any of the following symptoms during your pregnancy, they could be a sign of a complication. Seek medical help if you have:

  • Vaginal bleeding
  • Cramping, abdominal pain, and uterine tenderness
  • Signs of labor before 37 weeks, such as contractions, and an increase in vaginal discharge that’s clear, pink, or slightly bloody

Prevalence of Fibroids During Pregnancy

The reported incidence of fibroids in pregnancy ranges from 0.1% to 10.7% of all pregnancies. Fibroids during pregnancy are more likely to be encountered in patients who:

  • Are 35 years of age and older
  • Are overweight
  • Have had no previous children
  • Are Black

Fibroids and Postpartum

Fibroids often shrink after pregnancy. In one study, researchers found that three to six months after delivery, 70% of pregnant people who had live births saw their fibroids shrink more than 50%.

The reasons uterine fibroids may decrease or disappear in the postpartum period are not clearly understood yet, but it's thought that the mechanical and cellular changes that take place during birth can play a crucial role.

Impact on Recovery

Many studies show that having uterine fibroids increases your odds of having a cesarean section. That could be because the fibroids can keep the uterus from contracting and can also block your birth canal, slowing down the progress of your labor. If you had a cesarean section due to fibroid complications, your birth recovery will take longer than it would following a vaginal birth.

Breastfeeding

Ongoing breastfeeding seems to act as a protective factor against an increase in the size of uterine fibroids after pregnancy: Pregnant people who were lactating six months after delivery were more likely to have an unchanged or smaller fibroid diameter.

The protective effect of breastfeeding seems to be more evident for fibroids with a prepregnancy diameter of less than 32 millimeters (mm).

Frequently Asked Questions

How do you deal with fibroids during pregnancy?

During pregnancy, most medical and surgical treatments for uterine fibroids are ruled out due to the risk to the fetus. Bed rest, hydration, and mild pain relievers may be prescribed to help you manage symptoms of fibroids.

How can you prevent fibroids from growing during pregnancy?

Estrogen plays many important roles in pregnancy, from promoting fetal growth and development to preparing your breasts for lactation, but the increase in estrogen may also promote the growth of uterine fibroids. There's nothing you can do to control these hormonal changes.

By eating a healthy diet, cutting out refined grains (breads, cereals, pasta), and other processed foods, you may help to minimize problems associated with fibroids and other pregnancy complications like gestational diabetes

Why do fibroids cause bleeding during pregnancy?

Most of the time, the placenta is implanted (located) well away from the fibroids, and there is little or no increase in bleeding. Less commonly, the placenta is implanted over or near a fibroid. In those cases, bleeding in both early and late pregnancy can be more common. Even if this happens, most of these pregnancies still progress well.

What complications can happen during pregnancy when you have fibroids?

Fibroids do not always affect pregnancy. However, they can sometimes cause:

  • Miscarriage
  • Bleeding
  • Placenta previa (implantation of the placenta over the cervix)
  • Placental abruption (premature separation of the placenta from the uterus)
  • Preterm labor
  • Weak contractions
  • Cesarean section
  • Postpartum hemorrhage

A Word From Verywell

Uterine fibroids may affect your fertility. They may also impact your ability to carry a pregnancy to term. However, most pregnant people will experience no fertility issues or pregnancy complications as a result of these growths.

If you have fibroids and want to start a family, talk with your doctor about your options for treatment and your risks. Together, you can decide how to navigate your future pregnancy.

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