Understanding Uterine Fibroids and Pregnancy

Uterine fibroids are one of the many complications possible during pregnancy. They’re small, benign tumors that grow out of the muscle of the uterus. They can be either large or small and may change the shape and size of the uterus if they’re large enough. Uterine fibroids tend to form in groups, so where there’s one, there may be many. Here’s a look at understanding uterine fibroids. 

Types of Uterine Fibroids

Uterine fibroids are given different names depending on where they’re located. Intramural fibroids grow on the inside of the uterus, while subserosal fibroids develop on the outside. Less common and also inside are submucosal fibroids.

Fibroids Causes and Risk Factors

Women of any age can develop fibroids, but women in their childbearing or menopausal years, and those with a genetic predisposition, are more likely to develop larger fibroids. The hormones estrogen and progesterone, which increase during pregnancy and menopause, both influence the development of fibroids. Some women find that their fibroids shrink after pregnancy. African-American women are at a particularly risk of getting fibroids. Other risk factors include:

  • Beginning your period at an early age
  • Birth control
  • Being overweight
  • Insufficient vitamin D
  • Eating too much red meat and too little produce and dairy
  • Excessive alcohol consumption


Most fibroids are so small they cause no evident symptoms or prenatal complications. However, fibroids can cause problems related to menstruation, particularly if they’re large, including heavy menstrual bleeding, periods lasting much longer than normal, or unusual spotting. Women with fibroids may experience difficulty emptying the bladder and back or pelvic pain. Only in rare cases do fibroids become cancerous.

Prenatal Complications 

Fibroids don’t generally cause difficulties in regards to pregnancy. However, they may decrease fertility. Because of the hormonal changes during pregnancy, existing fibroids tend to grow larger. If fibroids, particularly submucosal fibroids, are very large and interfere with the fetus’ space or growth, complications may arise — including loss of pregnancy or placental abruption. 

It’s possible for the fetus to crowd out the fibroid, effectively killing the fibroid, especially if it loses blood supply. Women who experience this may have sudden labor-like contractions, which can cause miscarriage or early delivery. Women with prenatal fibroids may also experience heavy, unexplained vaginal bleeding and pain. Fibroids may interfere with a vaginal delivery by taking up areas needed to push the baby out. Fibroid may also grow into the uterus, making the baby’s position unsuitable for vaginal delivery. 


In most cases, fibroids that develop during pregnancy are left alone unless they’re causing serious maternal or fetal harm. In fact, very few fibroids require treatment at all. Treatment, which can be risky during pregnancy, must be more beneficial than hazardous. After delivery, if the fibroids remain and cause discomfort, pharmaceutical or surgical treatment may be possible. There are no known methods to prevent the development of fibroids. 

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