Polyhydramnios in Pregnancy




Meenakshi Lallar, Anam ul Haq, and Rajesh Nandal

The amniotic fluid surrounds the fetus and is essential for its continuous development and protection. The volume of amniotic fluid changes constantly during pregnancy, increasing from 35 ml at 12 weeks’ gestation to 250 ml at 17–18 weeks, and to 800 ml at term. After 38 weeks, the quantity of fluid decreases to about 250 ml by 43 weeks. Amniotic fluid balance is a consequence of complex interactions between fetal and maternal systems. Polyhydramnios develops as a consequence of disturbed equilibrium between production, fetal resorption, and secretion of amniotic fluid. Polyhydramnios is generally defined as amniotic fluid volume of 2000 ml or more at term. It is also defined as a state where the deepest vertical pocket of amniotic fluid measures more than or equal to 8 cm, or amniotic fluid index (AFI) of equal to or more than 24 cm, or above the 95th percentile for gestational age on ultrasound. The incidence of polyhydramnios has been estimated to range between 0.4 and 3.3 % . Maternal disorders, such as diabetes, in utero infections, drug usage, placental abnormalities, and fetal conditions like congenital and chromosomal abnormalities, Rh iso-immunization, and multiple gestations, are generally associated with half of the cases with polyhydramnios. However, in about half of the cases, no clear cause is found, and it is referred to as idiopathic polyhydramnios.


Polyhydramnios is the condition of having an excessive accumulation of amniotic fluid that surrounds the baby in the uterus. Polyhydramnios only happens in about 1 to 2 percent or 1 in 100 pregnancies. While most cases of polyhydramnios are mild and result from a gradual build-up of amniotic fluid during the second half of pregnancy more severe cases may cause shortness of breath, preterm labour and other symptoms.


  • Shortness of breath
  • Swelling in the lower extremities and abdominal wall
  • Uterine discomfort or contractions
  • Fetal malposition, such as breech presentation
  • Your health care provider may also suspect polyhydramnios if your uterus is excessively enlarged and they have trouble feeling the baby.

Ultrasound diagnosis

  • The vertical measurement of the deepest pocket of amniotic fluid that does not have of fetal parts in it is used to diagnose polyhydramnios. This will help classify polyhydramnios into mild, moderate and severe
  • In about 80% of cases the polyhydramnios is mild, in 15% moderate and in 5% severe.
  • Most cases of mild polyhydramnios the cause is not known, but when the cases are moderate or severe polyhydramnios are due to maternal or fetal problems.
  • In most cases, polyhydramnios develops late in the second or in the third trimester of pregnancy. Acute polyhydramnios at 16–22 weeks is mainly seen in association with twin-to-twin transfusion syndrome.

Some of the Known Causes of Polyhydramnios Include

  • A birth defect that affects the baby's gastrointestinal tract. The digestive tract begins at the mouth and ends at the anus. The oesophagus is the muscular tube that connects the back of the mouth to the stomach. Waste (faeces) is temporarily stored in the rectum before being passed out of the body through the anus. During a baby’s development, the digestive tract may fail to develop properly. Birth defects of the digestive tract include oesophageal atresia (obstruction of the oesophagus) and imperforate anus (malformations of the anus). These defects may occur together.
  • Most babies born with oesophageal atresia also have trachea-oesophageal fistula, which means the trachea (windpipe) leading to the lungs is connected to the oesophagus. The causes of these malformations are unknown, so prevention is not possible.
  • Maternal Diabetes
  • Twin-twin transfusion — a possible complication of identical twin pregnancies in which one twin receives too much blood and the other too little
  • A lack of red blood cells in the baby (fetal anaemia)
  • Blood incompatibilities between mother and baby
  • Infection during pregnancy
  • Often, however, the cause of polyhydramnios isn't clear.

Complications of Polyhydramnios is Associated With

  • Premature birth
  • Premature rupture of membranes or when your water breaks early
  • Placental abruption, when the placenta peels away from the inner wall of the uterus before delivery
  • Umbilical cord prolapses, when the umbilical cord drops into the vagina ahead of the baby
  • The earlier that polyhydramnios occurs in pregnancy and the greater the amount of excess amniotic fluid, the higher the risk of complications.


Mild cases of polyhydramnios rarely require treatment and may go away on their own. Even cases that cause discomfort can usually be managed without intervention.

If you experience preterm labour, shortness of breath or abdominal pain, you may need treatment potentially in the hospital.

Treatment may include

  • Drainage of excess amniotic fluid. Your health care provider may use amniocentesis to drain excess amniotic fluid from your uterus. This procedure carries a small risk of complications, including preterm labour, placental abruption and premature rupture of the membranes.
  • Medication. Your health care provider may prescribe the oral medication indomethacin (Indocin) to help reduce fetal urine production and amniotic fluid volume. Indomethacin isn't recommended beyond 31 weeks of pregnancy. Due to the risk of fetal heart problems, your baby's heart may need to be monitored with a fetal echocardiogram and Doppler ultrasound. Other side effects may include nausea, vomiting, acid reflux and inflammation of the lining of the stomach (gastritis).

After treatment, your doctor will still want to monitor your amniotic fluid level approximately every one to three weeks.

If you have mild to moderate polyhydramnios, you'll likely be able to carry your baby to term, delivering at 39 or 40 weeks. If you have severe polyhydramnios, your health care provider will talk with you about the appropriate timing of delivery, to avoid complications for you and your baby.

Polyhydramnios can be a stressful discovery during pregnancy. Work with your pregnancy care team to ensure that you and your baby receive the best possible care.

Quotes and Family Stories

“I can remember that I was surprised how big my belly was and wondered if this was normal and then my waters broke and I delivered my son at 28 weeks. I didn’t understand why this happened until my doctor talked to me and suspected Polyhydramnios. I was glad to a least have a reason why he came early…” Andrea –Miracle Mum of Steven and Aiden


Useful Links

Baby Center, Australia


Pregnancy, Birth and Baby, Australia


Confirmation Content

Disclaimer: This publication by Miracle Babies Foundation is intended solely for general education and assistance and it is it is not medical advice or a healthcare recommendation. It should not be used for the purpose of medical diagnosis or treatment for any individual condition. This publication has been developed by our Parent Advisory Team (all who are parents of premature and sick babies) and has been reviewed and approved by a Clinical Advisory Team. This publication is not a substitute for professional medical advice. Miracle Babies Foundation recommends that professional medical advice and services be sought out from a qualified healthcare provider familiar with your personal circumstances. To the extent permitted by law, Miracle Babies Foundation excludes and disclaims any liability of any kind (directly or indirectly arising) to any reader of this publication who acts or does not act in reliance wholly or partly on the content of this general publication. If you would like to provide any feedback on the information please email [email protected].