Polyhydramnios: High Amniotic Fluid During Pregnancy

Polyhydramnios or commonly referred to as “Poly,” is a relatively rare condition that happens in about one percent of pregnancies. Polyhydramnios occurs when excess amniotic fluid accumulates in the uterus during pregnancy. The excess in amniotic fluid is opposite of oligohydramnios which means there is low amniotic fluid. In most cases, polyhydramnios is harmless, but it does have the potential to cause serious pregnancy complications.

What are the symptoms of polyhydramnios?

A mild case of polyhydramnios may not cause any symptoms. It is okay because mild polyhydramnios typically does not result in any pregnancy complications.
Moderate to Severe Polyhydramnios may cause the following symptoms:

  • Difficulty breathing
  • Swelling in the lower extremities
  • Swelling of the vulva
  • Decreased urine production
  • Constipation
  • Heartburn
  • Feeling huge or tightness in the belly

The above symptoms result from an overly enlarged uterus exerting pressure on other organs.
Your doctor may be able to identify symptoms of polyhydramnios that you cannot. If your uterus is excessively large, (measuring two or more weeks ahead) or if your doctor has trouble feeling the baby or finding the baby’s heartbeat, you may have polyhydramnios.
Polyhydramnios can occur as early as 16 weeks of pregnancy, but most cases do not occur until later in pregnancy. An early appearance of polyhydramnios indicates a higher likelihood of pregnancy complications.


In many cases, the cause is unknown. Mild polyhydramnios is probably just caused by the gradual buildup of amniotic fluid over the course of pregnancy.
The following conditions could cause moderate to severe polyhydramnios:

  • A birth defect or congenital disability – Sometimes polyhydramnios is a side effect of a birth defect that impairs the baby’s ability to swallow. While inside the womb, babies will swallow amniotic fluid and then urinate it out, keeping the amount of amniotic fluid at a steady level. If the baby cannot swallow due to a genetic defect, amniotic fluid will build up.
  • Maternal diabetes – Elevated blood glucose levels can lead to an excessive buildup of amniotic fluid. This complication can happen in cases where the mother had diabetes before getting pregnant or becomes diabetic during pregnancy (gestational diabetes).
  • Twin To Twin Transfusion Syndrome (TTTS)  – If you are carrying identical twins, it’s possible that you could have a complication in which one twin is getting too much blood, and the other is getting too little.
  • Mismatched blood types – When a mother has the Rh-negative blood type, and her baby has the Rh-positive blood type, there is a risk of the baby developing, Rh-factor or Rh disease, a type of anemia. This disease can cause, among other complications, polyhydramnios.


As mentioned earlier, mild polyhydramnios usually does not cause complications. But in severe cases, there are certain risks, including:

Testing For Polyhydramnios

If your doctor suspects you have polyhydramnios, based on your symptoms or the appearance of your ultrasound, he or she will perform a more detailed ultrasound to estimate how much amniotic fluid is inside your uterus. If you are above the threshold, your doctor may also perform the following tests:


Treatment depends on the severity of the condition and what is causing it. Mild cases of polyhydramnios usually do not require any treatment. Your doctor will probably ask you to come in for extra checkups to make sure the condition does not become severe. But you should be able to deliver a healthy baby without complications and without inducing labor.
In severe cases, the treatment plan may focus on the underlying condition. If for example, your doctor determines that your polyhydramnios is a result of your baby’s heart rate, he or she might give you medication to correct the heart rate, thereby adjusting the polyhydramnios.
Polyhydramnios can be treated by regularly draining amniotic fluid from the uterus using a large needle. This procedure does carry a risk of complications, so your doctor will only recommend it if the danger of continuing the pregnancy with untreated polyhydramnios is greater than the risk of draining the fluid.
Polyhydramnios can also be treated with a medication that reduces the amount of urine the fetus produces. This drug does carry a risk of damaging the baby’s heart, so you will need to get regular checkups to monitor your baby’s heartbeat.
In some severe cases, your doctor may decide that the best course of action is to induce labor early, at 37 weeks, or even sooner.
Cases of moderate polyhydramnios found later in pregnancy can be treated with bed rest. Laying horizontal and resting is recommended to delay any preterm labor as long as possible. Many women find it hard to move or get around and describe it as feeling like they are about to “pop.” This feeling can be somewhat true when it comes to your water possibly breaking early because of the pressure.
It is important that you follow your doctor’s orders to help you and your baby have the best possible delivery.

Compiled using information from the following sources:

1. March of Dimes, Pregnancy Complications: Polyhydramnios.


2. NHS, Polyhydramnios (too much amniotic fluid).


3. Mayo Clinic, Diseases, and Conditions: Polyhydramnios.