Fibroids are benign tumors that grow in or on the uterus, or womb. They may impact fertility and pregnancy chances.

Uterine fibroids are very common. About 20 to 80 percent of women develop these noncancerous growths by age 50, and 30 percent of women between 25 and 44 have symptoms of fibroids. That means uterine fibroids are common during a woman’s childbearing years.

Read on to learn more about why fibroids develop and how they affect pregnancy.

Most women will experience no effects from fibroids during their pregnancy. However, a 2010 review suggests 10 to 30 percent of women with fibroids develop complications during pregnancy. Researchers note the most common complication of fibroids during pregnancy is pain. It’s seen most often in women with fibroids larger than 5 centimeters who are in their last two trimesters.

Fibroids may increase your risk for other complications during pregnancy and delivery. These include:

  • Fetal growth restriction. Large fibroids may prevent a fetus from growing fully due to decreased room in the womb.
  • Placental abruption. This occurs when the placenta breaks away from the uterine wall because it’s blocked by a fibroid. This reduces vital oxygen and nutrients.
  • Preterm delivery. Pain from fibroids may lead to uterine contractions, which can result in an early delivery.
  • Cesarean delivery. WomensHealth.gov estimates women with fibroids are six times more likely to need a cesarean delivery (C-section) than women who don’t have these growths.
  • Breech position. Because of the abnormal shape of the cavity, the baby may not be able to align for vaginal delivery.
  • Miscarriage. Research notes the chances for miscarriage are doubled in women with fibroids.

The majority of fibroids don’t change in size during pregnancy, but some do. In fact, one-third of uterine fibroids may grow in the first trimester, according to a 2010 review. Fibroid growth is possibly influenced by estrogen, and estrogen levels rise during pregnancy. This may lead to growth.

Still, for other women, fibroids may actually shrink during pregnancy. In a 2010 study, researchers found that 79 percent of fibroids that were present before a pregnancy decreased in size after delivery.

Many women who have fibroids can get pregnant naturally. Treatment may not even be necessary for conception.

In some cases, however, fibroids can impact your fertility. For example, submucosal fibroids, which are a type of fibroid that grows and bulges into the uterine cavity, increase your risk for infertility or pregnancy loss.

While fibroids may cause infertility for some women, other explanations for infertility are more common. If you’re having trouble conceiving or maintaining a pregnancy, your doctor may explore other possible causes before attributing the issue to fibroids.

Next steps if you’re trying to conceive with fibroids

Talk with your doctor about the size or position of any fibroids you have. Ask if they could cause problems with your attempts to get pregnant or the ability to carry a pregnancy. Likewise, ask your doctor if fibroid treatments can help improve your odds for pregnancy success.

During pregnancy, treatment for uterine fibroids is limited because of the risk to the fetus. Bed rest, hydration, and mild pain relievers may be prescribed to help expectant mothers manage symptoms of fibroids.

In very rare cases, a myomectomy can be performed in women in the second half of their pregnancies. This procedure removes fibroids from the outside of the uterus or from within the uterine wall while leaving the uterus intact. Fibroids growing in the uterine cavity are generally left in place due to the possible risks to the fetus.

How are fibroids treated before pregnancy to improve fertility?

Treating uterine fibroids before pregnancy may improve your fertility risk. The most common treatments for fibroids that preserve fertility include:

  • Myomectomy. This surgical procedure is used to remove fibroids. It may increase the need for cesarean delivery, and you’ll likely need to wait about three months following the procedure before attempting to conceive.
  • Hormonal birth control pills. While you’re on the pill, you won’t be able to become pregnant. But this contraceptive can help ease symptoms of the condition, such as heavy bleeding and painful periods.
  • Intrauterine device (IUD). Like the birth control pill, an IUD will prevent pregnancy as long as you’re using it. However, it can help eliminate some of symptoms while preserving fertility.
  • Gonadotropin-releasing hormone (Gn-RH) agonists. This type of medication blocks the production of the hormones that lead to ovulation and menstruation, so you won’t be able to become pregnant while taking this medication. It can help shrink fibroids.
  • Myolysis. This procedure uses an electric current, laser, or radio-frequency energy beam to shrink the blood vessels that feed the fibroids.

Other treatments are available for women with fibroids who may want to have children in the future. Each treatment carries its own risk and complications, so talk with your doctor about your options.

Likewise, ask your doctor how long you’ll have to wait before attempting to become pregnant after treatment. With some treatments, such as the birth control pill, you can try for pregnancy as soon as you stop using it. For others, there may be a waiting period.

You may not have any symptoms of fibroids. If you do have symptoms, the most common symptoms include:

  • heavy or painful periods
  • bleeding between periods (spotting)
  • anemia from heavy or long-term bleeding
  • prolonged periods
  • feeling “full” or a mild pressure in your lower abdomen
  • pain during sex
  • low back pain
  • constipation
  • reproductive issues, including infertility, miscarriage, and preterm labor
  • frequent urination
  • difficulty emptying your bladder

Fibroids may be felt during a pelvic exam. If your doctor suspects you have the noncancerous growths, they may order an imaging test, such as an ultrasound, to confirm the growths are indeed fibroids and not something else.

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

If you have fibroids and wish to start a family, talk with your doctor about your options for treatment and your risks. Together, the two of you can decide what’s safest for your future pregnancy.

While you can’t prevent fibroids, a healthy lifestyle may lower your risk. Likewise, a healthy lifestyle, which includes maintaining a healthy weight, may lower your risk for fertility issues and high-risk pregnancies.