Kyle Traynor, M.D., Obstetrics & Gynecology, Mayo Clinic

There are a number of possible causes for polyhydramnios, ranging from maternal metabolic abnormalities, like gestational diabetes, to fetal congenital abnormalities. Provided your physician has ruled out the more concerning causes for polyhydramnios, then the issue becomes the effects of the polyhydramnios itself. There are three significant complications that can arise from the presence of excess amniotic fluid.

First, the increased volume of fluid causes the uterus to stretch beyond normal size to accommodate the excess fluid. That uterine stretching can result in contractions, and in your case, being 32 weeks pregnant, it increases the risk of preterm labor and preterm delivery. (Preterm labor refers to contractions that begin to open the cervix before week 37.) You should be particularly aware of regular, predictable and painful contractions, which could be a sign of preterm labor. If you notice contractions, contact your health care provider right away.

Second, the extra fluid present within the amniotic sac can potentially lead to a condition known as malpresentation. In the vast majority of pregnancies, the baby is in the head-down (cephalic) position when labor begins. This is considered the safest position to allow for a normal vaginal delivery. However, in a case of polyhydramnios, the excess fluid may give the baby more room to move into another position, such as a breech position in which the baby's bottom or feet are leading the way into the birth canal. This situation often results in the need for a cesarean delivery.

The third major concern with polyhydramnios is the possibility of umbilical cord prolapse. This is a situation in which the umbilical cord -- the baby's connection to the placenta and its supply of oxygen and nutrition -- enters the birth canal before the baby's head. The risk for umbilical cord prolapse is higher than normal when there is polyhydramnios.

When the bag of water breaks -- either breaking on its own (spontaneous rupture of the membranes) or being broken during labor by your health care provider (artificial rupture of the membranes) -- the excess fluid in cases of polyhydramnios can sweep the umbilical cord downward, causing it to enter the birth canal before the baby's head. When this happens, the baby can put pressure on the cord as he or she passes through the cervix and vagina during labor and delivery. Pressure on the cord reduces or cuts off blood flow from the placenta to the baby, decreasing the baby's oxygen supply. Umbilical cord prolapse is an obstetrical emergency that requires rapid delivery by cesarean.

If you don't experience spontaneous rupture of the membranes, your health care team can decrease the risk of umbilical cord prolapse by waiting to artificially rupture the membranes until the baby's head has entered and become fully engaged within the birth canal. At that point, the umbilical cord is generally not considered to be at risk for prolapse, and it's considered safe to rupture the membranes.

You may find it helpful to discuss the possible complications of polyhydramnios with your health care provider. Talk with him or her about the specific signs and symptoms to watch for that may signal preterm labor, and what you should do if you experience them. Have a conversation about what you can expect if the baby isn't in the head-down position when you go into labor. And, finally, discuss the risk of umbilical cord prolapse and how that situation would be handled by your health care team.

Keep in mind, too, that although these complications of polyhydramnios are possible, they aren't common. Once the concerning causes for polyhydramnios have been ruled out, and if the polyhydramnios is not too severe, it is likely that the remainder of your pregnancy will be normal and your labor and delivery will be uneventful.

Kyle Traynor, M.D., Obstetrics & Gynecology, Mayo Clinic, Rochester, Minn.

Medical Edge from Mayo Clinic is an educational resource and doesn't replace regular medical care.


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Excess Amniotic Fluid Can Cause Pregnancy Complications