Polyhydramnios

Polyhydramnios is a condition in which there is too much amniotic fluid during pregnancy, the fluid that surrounds the developing fetus. Excess amniotic fluid can put both mother and baby at risk of complications.

The condition may be isolated, meaning there are no other health issues, or it may occur as a result of other maternal or fetal conditions, including fetal birth defects or genetic abnormalities.

While polyhydramnios can occur at any time during pregnancy, it is most common in the second and third trimesters. The condition can range from mild to severe. The earlier it occurs and the greater the volume of amniotic fluid, the higher the risk of complications.

Polyhydramnios is also sometimes called hydramnios.

The Importance of Amniotic Fluid

Amniotic fluid levels are an important indicator of fetal health. As a result, your amniotic fluid level is regularly assessed as part of your routine prenatal care, to help identify any potential complications early.

Amniotic fluid consists primarily of fetal urine. During development, your baby breathes in and swallows amniotic fluid, helping the fetal lungs and other organs develop properly. The amniotic fluid and the baby are contained within the amniotic sac, sometimes referred to as the “bag of water,” inside the uterus.  

Some important functions of amniotic fluid include:

• Development of the fetal lungs, digestive system and kidneys
• Provides room for fetal growth and movement, enabling proper muscle and limb development
• Protects the umbilical cord from being compressed, cutting off food and oxygen from the placenta to the growing fetus

Abnormal amniotic fluid levels during pregnancy include both polyhydramnios, where there is too much fluid, and a condition known as oligohydramnios, where there is too little amniotic fluid.

How does too much amniotic fluid affect my pregnancy and my baby?

Complications caused by too much amniotic fluid range from mild to severe, depending on the amount of excess fluid and the underlying cause.  

Risks to mother and baby include:

• Preterm contractions and labor
• Premature rupture of membranes (PROM) (your water breaks early)
• Placental abruption, where the placenta pulls away from the uterine wall before birth
• Umbilical cord prolapse, when the umbilical cord moves into the vagina before the fetus and is compressed by the baby during labor, cutting off the baby’s blood and oxygen supply
• Baby grows too quickly and too large (macrosomia)
• Heavy maternal bleeding after delivery
• Fetus is abnormally positioned, requiring cesarean delivery (feet or bottom first, for example, known as breech presentation)
• Maternal respiratory distress
• Stillbirth

Symptoms

In mild cases, there may be no symptoms present.

In more severe cases, the buildup of fluids causes the uterus to become enlarged, putting pressure on nearby organs. Symptoms may include:

• Shortness of breath or severe breathing difficulties
• Larger-than-normal uterus for gestational date
• Painful preterm contractions or uterine discomfort
• Inability to hear the fetal heartbeat
• Fetal malposition, such as breech presentation
• Doctor has difficulty feeling the baby

Cause and Prevalence

Excess amniotic fluid occurs in an estimated 1 to 2 percent of all pregnancies.

Excess fluid can result from too much fluid being produced, not enough fluid being excreted, or both. It can be caused by problems with the fetus, such as birth defects that affect the baby’s ability to swallow or process amniotic fluid, or by maternal health issues.

Common causes include:

• Birth defects of the gastrointestinal (GI) system that block fluid passage, such as duodenal atresia and stenosis and esophageal atresia with tracheoesophageal fistula
• Birth defects of the central nervous system (brain and spinal column), such as microcephaly or arthrogryposis, that cause problems swallowing
• Birth defects affecting the fetal heart, lungs or kidneys, such as pleural effusion, congenital diaphragmatic hernia (CDH), CPAM, or CHAOS – by increased pressure in the chest compressing the esophagus preventing swallowing
• Maternal diabetes, which can cause the baby’s urine output to increase
• Twin-twin transfusion syndrome (TTTS), a condition in which identical twins share one placenta and one twin receives too much blood and the other too little
• Fetal anemia (lack of red blood cells) in cases where it results in heart failure and hydrops
• Infection during pregnancy
• Genetic conditions

In many cases, the cause is unknown.

Diagnosis

Your doctor may suspect polyhydramnios based on symptoms present or ultrasound findings. The diagnosis is confirmed by measuring the amount of amniotic fluid in the uterus using detailed ultrasound imaging. Blood tests may be run to look for underlying maternal conditions causing the excess fluid.

If you are diagnosed with polyhydramnios, you may be referred to a fetal center for further evaluation and to look for any fetal abnormalities.

At Texas Children’s Fetal Center, we arrange for you to visit as quickly as possible for a comprehensive assessment by a team of specialists experienced in diagnosing and treating these rare amniotic fluid conditions, including maternal-fetal medicine (MFM) physicians, fetal imaging experts, genetic counselors, surgeons, neonatologists, fetal cardiologists, and nephrologists (kidney specialists).

Additional testing may include:

• High-resolution anatomy ultrasound to evaluate the condition, assess fetal growth and development, and identify any birth defects, such as a malformation of the GI tract
• Ultra-fast MRI for a more detailed view of fetal anatomy and function
• Fetal echocardiogram to evaluate your baby’s heart structure and function
• Amniocentesis and chromosomal analysis to screen for genetic abnormalities
• Doppler ultrasound to evaluate the baby’s blood flow

Our specialists will then meet with you about your results, answer any questions your family has, and discuss treatment recommendations.

A diagnosis of any underlying fetal birth defects during pregnancy enables your family and your healthcare team to plan ahead for the special needs of your baby at birth and to arrange for the earliest possible treatment.

Treatment During Pregnancy

You and your baby will be closely monitored throughout pregnancy to watch for signs of complications. Testing may include:

• More frequent ultrasounds to assess fetal growth and amniotic fluid volume
• “Nonstress” tests to monitor fetal activity and heart rate

Treatment will depend on the severity and cause of the amniotic fluid buildup. Treatment may include:

• Management of underlying maternal disorders, such as diabetes, to control the amniotic fluid level and the growth of the baby
• Medications to reduce fetal urine production
• Amnioreduction, a procedure used in severe cases to withdraw amniotic fluid, reducing the risk of preterm labor (similar to an amniocentesis)
• Management of underlying birth defects or genetic abnormalities and preparations for specialized care at birth, to optimize fetal outcomes
• Hospitalization to manage complications and prevent premature birth
• Early delivery, if needed, for the health and safety of you and your baby

Delivery

Increased amniotic fluid increases the risk of serious maternal and fetal complications at delivery. We recommend delivery at a hospital with the specialized expertise and resources required to treat these high-risk deliveries, including the highest level neonatal intensive care unit (NICU), if needed.

Delivery and postnatal care should be carefully planned and coordinated with a team of maternal-fetal medicine specialists, neonatologists, and pediatric specialists experienced in working together to treat pregnancies involving rare amniotic fluid conditions, and any associated birth defects, ensuring the best possible care beginning at birth.

Our fetal center team works closely with pediatric experts from Texas Children’s Hospital, consistently ranked one of the best children’s hospitals in the nation by U.S. News & World Report.

Treatment After Birth

Treatment needs at birth vary for each baby depending on the severity and underlying cause of the excess amniotic fluid and the presence of any associated birth defects or genetic conditions.

In severe cases, your newborn may require specialized care in the NICU and surgery soon after birth to repair a congenital abnormality, such as a gastrointestinal blockage, lung masses or congenital diaphragmatic hernia.

Postnatal Care Team

A unique and distinct advantage for mothers delivering at Texas Children’s Pavilion for Women is our location inside one of the largest and most renowned children’s hospitals in the world, for seamless access to the critical care services and specialists your child may need.

For babies with rare fetal conditions such as polyhydramnios, this means no transfers during critical postnatal periods. It also means that the pediatric experts responsible for treating your child have been an integral part of their care team since before birth.

Depending on the severity and underlying cause of polyhydramnios, your baby’s postnatal care team may include:

• Neonatologist
• Pediatric surgeon
• Pulmonologist
• Cardiologist
• Gastroenterologist
• Nephrologist (kidney disorders)

Texas Children’s is ranked number one in the nation in pediatric cardiology and heart surgery, number one in pulmonary care, number two in nephrology (kidney disorders) and number two in gastroenterology by U.S. News and World Report. All of the hospital’s subspecialties rank in the top 10.

Research

Our researchers are continually working to better understand the causes of polyhydramnios and improve treatment options and outcomes for families around the world facing this diagnosis.

Learn more about our recent study on the use of amnioreduction in cases of polyhydramnios.

Why Texas Children’s Fetal Center?

• A single location for expert maternal, fetal and pediatric care. At Texas Children’s Hospital, mother and baby can get the specialized care required for the diagnosis and treatment of polyhydramnios – and any underlying maternal or fetal conditions – all in one location, for highly coordinated care and treatment, including immediate access to our renowned level IV neonatal intensive care unit (NICU).
• A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, fetal imaging specialists, neonatologists, genetic counselors, pediatric experts and others who work in concert to care for you and your baby every step of the way, using protocols we’ve developed over the years. With their combined expertise and unified approach, they offer the best possible care and outcomes for pregnancies complicated by polyhydramnios.
• We care for your child’s needs at every stage of life. Our comprehensive approach starts with your first prenatal visit and continues through your child’s delivery, postnatal care, and beyond, when needed, thanks to one of the nation’s leading teams of fetal and pediatric specialists for the treatment of rare fetal conditions and birth defects.