Can Fibroids Be In The Way of The Baby?
It is very ethnic dependent: African American Women are more likely to have uterine fibroids in pregnancy that Caucasian women. 18% of African American women will have uterine fibroids in pregnancy, and only about 5-8% of Caucasian women. You may or may not know that you have a fibroid, if it is large, such as over 2.5 inches (5 centimeters) then it's very likely your gyno will feel it on examination. If you have a smaller fibroid, it's most likely to only be detected on ultrasound, but no on examination. So you may not even know if your pregnancy is complicated by uterine fibroids. But if you do have a fibroid you have about an 8% chance of having a miscarriage. If you have more than one fibroid the risk of miscarrying raises to about 23%, so taking care of uterine fibroid before you plan a pregnancy may be something you want to gab with your gyno about.
Uterine fibroids seem to respond to hormones with growth, and the estrogen and progesterone levels in pregnancy are high. It is thought that estrogen is probably stimulatory to the growth of fibroids. One study showed DepoProvera progesterone users had greater fibroid growth, but most studies refute that charge. In pregnancy the fibroids usually grow in the first trimester, but they do tend to then either grow no further or actually shrink. In some studies the amount of growth so varied that some grew in early pregnancy, others in later pregnancy, and there was no direct relationship with stage of pregnancy, location of the fibroid, initial size of the fibroids, or symptoms. So you and your gyno will have to track your fibroids individually, as there is no universal rule to rely on.
Although many women will have uterine fibroids during pregnancy, it's not common that the uterine fibroids will cause symptoms or pain. There is a condition called degeneration, it can be seen on ultrasound as dark patches within the fibroid which appears a dense brighter color.
Oddly fibroids also are somehow related to our weight. If your BMI (height per weight) is high, you are more likely to have fibroid growth. This may be related to hormonal differences in those women who are overweight or obese, or related to other hormones which are expressed in our fat. In pregnancy, women do gain weight, and it may be the fibroids are then growing in response to weight gain and not just in response to hormone changes. Cigarette smokers have decreased risk of having a uterine fibroid. No one knows why smoking would decrease the risk that your uterine fibroid has grown, but it might be a secondary effect to the lower levels of estrogen, due to how the estrogen is metabolized, in smokers.
Ultimately whether fibroids are in the way of a potential or ongoing pregnancy has more to do with the actual size and location within the uterus than the fact alone that there is a fibroid. Many studies have shown that pregnancy out come is very good with uterine fibroids even uterine fibroids that are quite large. Recent studies have shown there is no difference in infections, c-sections, premature rupture of membranes; but with fibroids present in pregnancy in this same study there was more premature birth, bleeding in pregnancy, and there was more placenta previa (placenta covering the cervix). And for women who have had prior uterine surgery to remove fibroids, whether or not there are remaining fibroids, the uterine wall is more likely to rupture during pregnancy and labor than if no surgery had been done. Interestingly the studies show more risk for singleton pregnancies than for women carrying twins. As with many of our discussions, we have to end with a caution, don't make decisions by reading and studying alone. Make a decision regarding your fibroids with your own gyno.