Fibroids--also called leiomyomas, fibromyomas and myomas--are masses of muscle and fibrous tissue that grow on or in the wall of the uterus. Fibroids are common; MayoClinic.com reports that as many as three out of four women have uterine fibroids sometime during their lives. During pregnancy, fibroids usually cause only mild or no symptoms, and do not harm the fetus. In some cases, however, fibroids can wreak some havoc.
Abdominal Discomfort
A fibroid can bring additional discomfort to the ever-increasing pressure and weight of a growing fetus on a woman's abdomen. Part of the discomfort arises from additional pressure in the abdomen due to the mass of the fibroid. Uterine fibroids often grow in the beginning of pregnancy, largely due to increased blood flow to the uterus. In the second trimester, they can outgrow their blood supply and degenerate, which often results in pain. According to MayoClinic.com, abdominal pain can also occur when a fibroid that is growing out of the uterus on a stalk-like projection twists. This twisting can result in a sudden, sharp pain.
Bleeding
Uterine fibroids can cause excessive bleeding at any time during pregnancy. Blood loss during pregnancy can be risky for the health of the mother as it can contribute to lower iron levels and blood count, or anemia. These problems already commonly occur during pregnancy due to the fetus's demands on the mother's blood supply. When compounded by blood loss of whatever cause, these blood indices can reach dangerously low levels for the mother. Women with fibroids who experience bleeding during pregnancy must be monitored closely by their obstetrician to determine whether any treatment is necessary.
Problems With Delivery
Depending on their size and position in the uterus, some fibroids can cause problems during delivery. Babies that share space in the womb with a fibroid are more likely to be in breech presentation, which means feet- or bottom-down instead of the usual head-down. Breech babies are usually delivered by cesarean section. Cesarean sections must also be performed in cases where a fibroid blocks the passage of the baby out of the uterus. According to WomensHealth.gov, the need for a cesarean section is six times greater for women with fibroids.
Fibroids can also interfere with the normal expansion of the uterus, causing premature birth. According to PreconceptionWeekly.com, the birth is usually only two to three weeks early, which does not generally cause long-term problems for the baby.
Finally, placental abruption can occur if the placenta implants on top of a fibroid. Placental abruption, which means that the placenta prematurely separates from the uterine wall, can be life-threatening for the mother and the baby.
