Before reading this list of possible complications, it is important to remember that most babies born to women suffering from MAs encounter none of these problems. These are simply possibilities to keep in mind, and most of them come from the potential poor attachment/blood supply of the placenta, or the lack of space.
a. Miscarriage: Spontaneous abortion is very common, especially with the septate uterus, because of blood flow disruptions and possibly hormonal receptor abnormalities. The normal miscarriage rate for a woman with no fertility or anatomical problems is 20%, or 1 out of 5 pregnancies lost. In the septate uterus, which has the worst pregnancy outcomes, some studies show a miscarriage rate approaching 90%.
b. Incompetent cervix: As many as 20% of anomalous uteri may have additional problems, such as incompetent or weak cervix. Such cervices tend to give way between 16 and 22 weeks’ gestation. A woman with a known MA should ask her OB to check for this possibility. Cerclage—sewing a purse stitch around the cervix to keep it closed—is the most common remedy.
c. Placenta previa: Because of the tight quarters in an abnormal uterus, it is a little more common for the placenta to ride low and cover the inner cervical os. This condition poses a bleeding risk, but may correct itself as the pregnancy advances and the uterus stretches upward.
d. Abruptio placenta: Because of the abnormal configuration, contractions and vasculature within an abnormal uterus, problems with its attachment to the uterine wall may arise.
e. Premature labor: Although no one knows all the causes of premature labor, expansion restrictions may be one reason why an anomalous uterus is more prone to it. Another may be disorganized contractions of the abnormal muscle in a septum.
f. Abnormal fetal lie: Breech position is very common in an abnormally shaped uterus, possibly because there is more room for limbs at the bottom, or because the fetus loses its ability to roll 180° earlier than a fetus in a normal uterus.
g. Intrauterine growth restriction (IUGR): Again, because of the possible placental vascular insufficiency, the fetus may not get all the nutrients it needs, and may be small for dates. One form of IUGR tends to spare the brain, and the fetus, if born prematurely, does quite well despite the small size.
Should I see a regular OB-GYN during pregnancy?
While it should be remembered that many women with uterine anomalies have no trouble at all during pregnancy, one can never go wrong erring on the side of caution. If the MA is a severe one (a deep SU or BU, or any UU), it might be wise to at least consult with a high-risk specialist (perinatologist) early in the pregnancy, or have one co-manage your case along with your OB-GYN. Or you might simply interview your OB-GYN and find out how much MA experience he or she has, what his or her philosophy of care is, and whether or not you feel comfortable with it.
Expect to have your cervix length evaluated (sometimes a cervix weakens when the baby is crowded) and possibly treated with a purse stitch (cerclage) if it begins to open up in the second trimester. You may also expect to be monitored for premature labor, intrauterine growth retardation and abnormal fetal lie during your pregnancy; these pregnancy complications are more common with müllerian anomalies.