Are Fibroids Dangerous In Pregnancy?

Uterine fibroids tend to affect women during their childbearing years. This is a poor state of affairs for the woman who is trying to conceive, and not terrific for the woman who has already conceived and hopes to have a successful obstetric outcome. Fibroids may cause you no harm at all or cause you a great deal of trouble.

For one thing, fibroids may increase the risk for first or second trimester miscarriage and are also often responsible for preterm labor, at anywhere between 20 to 37 weeks gestation. Women without fibroids have a preterm labor rate of 8% at 37 weeks gestation, while women with fibroids have been estimated to have a preterm labor rate from 12% to 20% depending on the results of various studies on the topic.

Four Ways

Pregnancy and fibroids appear to be in conflict in four quite different ways. The issues may start with implantation. If there are one or more fibroids adhering to the wall of the uterus, the fertilized egg may not find a place to implant inside the uterus. In this case, the result is an immediate miscarriage.

Sometimes, the problems start way before implantation. If fibroids are close to or blocking the opening of the fallopian tubes, the sperm can’t make its way to the egg and the egg can’t come down, either. Sperm and egg are destined never to meet in such a case and pregnancy is not possible.

Then there is the fertilized egg that succeeds in implanting to the uterine wall but is then situated quite close to a fibroid. If the fibroid should continue to grow it may begin to leach nutrients the fetus needs to support its development. The fibroid may also begin to crowd out the fetus. The fetus isn’t equipped to share and this situation may cause a miscarriage to occur.

Six Fold

Let’s say you make it to delivery time and the fetus is still healthy and well. You’re not home safe, yet. Uterine fibroids may enlarge and block the birth canal, making labor difficult and a vaginal delivery all but impossible. In this case, a cesarean delivery may become necessary. In fact, a woman with uterine fibroids is estimated to have a six-fold increase in her risk for delivering by C-section.  

One reason that fibroids are problematic during pregnancy is the extra estrogen and progesterone that are produced by a woman’s body during this time. These hormones cause the fibroids to grow. After delivery, the fibroids tend to shrink with no intervention, because the hormone levels are then decreased.