What is Hydramnios?

Medically Reviewed by Poonam Sachdev on April 08, 2022
Written by Alyssa Anderson
5 min read

Hydramnios is a condition specific to pregnant women. It occurs when you have too much amniotic fluid around your baby. 

It occurs in around 1% of pregnancies. 

Polyhydramnios is a different word for hydramnios. The two terms can be used interchangeably. 

A normal amount of amniotic fluid is between one half and one full quart — found within the amniotic sac in your womb. Having much more than the average amount at any given time in your pregnancy counts as polyhydramnios. 

The condition can be mild, moderate, or severe. In general, the earlier the condition begins, the more fluid that’s likely to build up. More fluid means that you have a greater risk of complications and birth defects. 

Polyhydramnios can have a number of different causes, some linked to the mother’s health and others to the child. 

In a normal pregnancy, amniotic fluid is produced by the baby’s lungs and kidneys. As it grows, the baby swallows the fluid and urinates it — along with waste products. Then, it’s removed from the amniotic sac by the placenta. In all cases of hydramnios, part of this process is disrupted. 

For example, your baby may be producing too much amniotic fluid, or there are problems processing and removing it. 

Possible causes include: 

  • Gestational diabetes. 
  • Infections during the pregnancy. This includes parvovirus.
  • Certain digestive problems. These include birth defects in the gastrointestinal tract.
  • Problems swallowing. These are possibly due to defects in the central nervous system or from chromosomal abnormalities.
  • Heart failure.
  • Bartter Syndrome. A genetic condition that affects fetal kidney development.
  • Twin-Twin Syndrome. An uneven distribution of amniotic fluid between twins where one gets too much fluid
  • Hemolytic anemia. A condition that causes too much heart activity and leads to too much urine output. 

Between 60% and 70% of all cases don’t have a detectable cause — this is known as idiopathic polyhydramnios. 

Hydramnios is most commonly diagnosed by ultrasound. This might happen at a routine appointment or if your doctor is investigating other symptoms. 

Your doctor may also specifically test for this condition if your uterus becomes unexpectedly large very quickly or if you have trouble feeling the baby.  

The technician will check pockets of the fluid with soundwaves to figure out the total amount. Ultrasounds are also helpful in determining the cause of hydramnios — particularly if it’s occurring because of a birth defect.  

With mild polyhydramnios, you may not experience a single symptom before you’re diagnosed. However, you’re likely to experience more symptoms the longer the condition lasts and the more fluid builds up.  

These symptoms can include: 

  • Stomach discomfort
  • Premature labor pains
  • A larger than normal uterus for your pregnancy stage
  • Shortness of breath

The fluid — and the symptoms — can either accumulate slowly or appear all at once. In the second case, you might suddenly notice a large amount of swelling near your baby that appeared too quickly to be normal.  

In more severe cases, polyhydramnios can lead to serious complications with your pregnancy and is linked to an increased rate of birth defects in your child. For example, around 20% of all infants affected by hydramnios have some kind of congenital anomaly — or heart defect. 

Other complications include:  

  • Premature birth.
  • An out-of-position fetus.  
  • Stillbirth. 
  • Placental abruption. This occurs when the amniotic sac becomes detached from the uterine wall. 
  • Umbilical cord prolapse. This occurs when your umbilical cord falls into your vagina.
  • Premature breaking of the amniotic sac.
  • The need for a C-section.
  • Heavy post-delivery bleeding. This is because of a lack of muscle tone in your uterus after being stretched by the extra fluid. 

The treatment for your hydramnios depends on the severity of your condition. If your condition is mild, then you might not need any treatment at all. 

In more severe cases, your doctor will need to determine the best treatment strategy based on your particular pregnancy. If the cause is known and treatable — like gestational diabetes — then treating that is the best way to manage the condition. 

In other cases, treatment can include:

  • Medicine. There’s a medicine available to reduce how much urine your baby produces — therefore limiting the amount of amniotic fluid. The medication is called indomethacin and isn’t recommended after the first 31 weeks of your pregnancy. 
  • Removal of fluid. This process is called amnioreduction by amniocentesis. A large needle is used, as with amniocentesis. The procedure may need to be done more than once throughout your pregnancy. 
  • Early Delivery. This will differ greatly from one pregnancy to the next. In general, the goal of treatment is to get you as close to term — 39 to 40 weeks — as possible.  
  • Fetal echocardiogram. This is used to monitor the development of your baby’s heart because of the higher risk of an abnormality.  

In all cases of hydramnios — mild or severe, before or after treatment — your doctor will want to carefully monitor your uterus, amniotic fluid, and developing infant. This will require more visits than normal. You’ll likely have an appointment every one to three weeks.   

You may want to make some changes to your pregnancy schedule once you’ve been diagnosed with polyhydramnios. These can include: 

  • Beginning your maternity leave early. This will get you off of your feet and allow you to get more rest, lowering your chances of developing complications. 
  • Have your house ready for an early baby. You can no longer plan as though you’ll make it to term. Make sure that you have all of the supplies and space you need for your baby ready to go. 
  • Have an early birth plan ready. Discuss with your partner, midwife, doctor, and the rest of your birthing team what to do if your water breaks early. 
  • Discuss any discomfort with your doctor. Some of the symptoms of hydramnios can be uncomfortable — talk to your doctor for the best advice on getting relief.  

The most important thing is to not worry too much about this condition. In most cases — with careful monitoring — your pregnancy will continue with few serious complications. 

Contact your doctor or midwife as soon as you notice any sudden swelling around your baby.

You should also tell your doctor if you have a family history of gestational diabetes or any fetal disorders associated with this condition. 

In the case of pregnancy, it’s always best to seek help and advice if you have any serious concerns.