Low Amniotic Fluid (Oligohydramnios): Causes, Signs & Treatment

Low amniotic fluid in pregnancy can be worrying, especially when you are unsure what it means for your baby. Amniotic fluid is a water-like fluid that surrounds the baby while it grows in the uterus and helps in its development. Amniotic fluid cushions the baby, allows the baby to move and prevents the umbilical cord from being compressed. As per the Cleveland Clinic, when the fluid level falls below the expected amount for the stage of pregnancy, the condition is known as oligohydramnios (1). Low amniotic fluid reasons can vary, ranging from leaking amniotic fluid and problems with the placenta to certain maternal or fetal conditions, although sometimes no specific cause is found.

What Is Amniotic Fluid?

During pregnancy, the foetus grows and develops inside a fluid-filled bag called the amniotic sac. This amniotic sac is filled with amniotic fluid. Amniotic fluid cushions the baby and protects it from all sorts of infections. It also protects the baby from getting hurt if the mother-to-be experiences a blow to her tummy. It keeps the temperature inside the womb constant and also helps in the development of the baby’s muscles, limbs, lungs and digestive system (2).

As your baby begins to breathe in the second trimester, he will start swallowing the amniotic fluid and later pass it as urine. That’s how a baby maintains the volume of amniotic fluid around himself.

What Is Oligohydramnios?

By Oligohydramnios definition, we mean that it is a condition where the volume of amniotic fluid inside the amniotic sac is too low for the baby’s gestational age (3). Doctors can measure the amount of amniotic fluid inside you through amniotic fluid index evaluation or deep pocket measurements. If the volume of liquid is less than 500ml in pregnant women during the 32nd to 36th week, then oligohydramnios is suspected.

Oligohydramnios is diagnosed when:

• The amniotic fluid volume is less than 500 ml
• The maximum vertical pocket is less than 2 cm
• The amniotic fluid index is less than 5 cm.

How Common Is Oligohydramnios?

The percentage of women suffering from oligohydramnios is close to 8%, and it can occur at any time during pregnancy, though it is most common during the last trimester. If you are 2 weeks from your due date of delivery, then there is a high chance of your amniotic fluid becoming low. Around 12% of pregnancies that cross 41 weeks of gestation may encounter complications due to Oligohydramnios.

What Role Does Amniotic Fluid Play in the Development of the Baby?

Amniotic fluid performs several functions such as:

• When the baby moves around freely in the amniotic fluid, it helps in bone and muscle development.
• When the baby breathes the amniotic fluid in and out, it helps in the development of the lungs.
• When the baby starts swallowing the fluid and peeing it out later, it helps in the development of the digestive system.
• Amniotic fluid protects the umbilical cord from getting compressed. As a result, the flow of nutrition from the mother to the baby for its overall development is not compromised.
• The amniotic fluid also acts as a lubricant and helps in the development of fragile body parts that grow together, like fingers and toes.

How Much Amniotic Fluid Is Normal When Pregnant?

The volume of amniotic fluid continues to increase until the 36th week of pregnancy, and it measures anywhere between 800 and 1000 ml, which is considered normal. After the 36th week of gestation, the volume of amniotic fluid starts to fall in preparation for birth. The amount of amniotic fluid goes down to 600 ml by the 40th week of gestation, or at full term, and that too is normal.

Symptoms of Low Amniotic Fluid

During your regular check-ups, your doctor will keep a close watch on your belly. If your stomach is not growing the way it should, then your doctor may ask you to go for a scan to check the development or growth of the baby. Now, that’s one (and important) symptom. Other symptoms are:

• Fluctuating blood pressure
• First baby born with low birth weight or smaller in size
• Constant leakage of fluid from the vagina
• Both mother and child not gaining enough weight
• Baby’s growth is prolonged

Causes of Oligohydramnios

Low levels of amniotic fluid are most common during the third trimester. The causes for the same could be any of the following (4):

• Water-breaking: If your amniotic sac tears off and fluid flows out, it is called water breaking. This usually happens in and around the time of delivery. If you haven’t quite reached the delivery time, then your doctor may give you antibiotics to protect you and your baby from infection while you wait for the delivery date to close in. If you have crossed the 38th week of pregnancy, based on your condition, the doctor may also suggest inducing labour.
• Health hazard: If your baby has some health issues, then the volume of amniotic fluid may become low. Especially during the second-trimester scan, babies are diagnosed with kidney, heart or chromosomal abnormalities. This becomes obvious in the scan if your baby is passing very little urine. Your doctor may also suggest another test called amniocentesis to be sure.
• Issues with placenta: If you have diabetes, high blood pressure, lupus or preeclampsia, then your placenta may fail to supply enough blood and nutrition to your baby. In this case, the volume of amniotic fluid may decrease, and you may have to be under strict supervision (5).
• Medication: Some medicines must be avoided during pregnancy as they cause low amniotic fluid. Drugs for high blood pressure and an anti-inflammatory like ibuprofen are not prescribed during pregnancy.
• Identical twins: If identical twins share a placenta, then sometimes there may be an issue of low amniotic fluid. In this case, the baby with extra blood will get access to the amniotic fluid, while the other will not get enough.

If your doctor can rule out all the above causes, then there is nothing to worry about. Many a time it has been observed that low amniotic fluid level is due to dehydration during summers. So drinking plenty of water and taking enough rest will help.

Diagnosis Methods for Oligohydramnios

The following methods can be used to detect oligohydramnios (6).

• Ultrasound Scans: The best and first diagnosis for oligohydramnios is an ultrasound scan. During the ultrasound, the amniotic fluid volume is measured in four different parts of your uterus, and then all four values are put together to calculate the amniotic fluid index or AFI. Also, the kidneys and bladder of the baby are assessed to look for any anomalies. The ultrasound diagnosis also includes the assessment of the baby’s growth, which is done by measuring the abdominal circumference, head circumference, and the femur length.
• Amniotic Fluid Index (AFI): AFI is measured through ultrasonography and is a widespread and safe test. This test helps your doctor to determine the volume of amniotic fluid in your uterus.
• Sterile Speculum Examination: This test is performed by the doctor to check for a range of motion which is caused by a tear of the amniotic sac membrane, which in turn results in leakage of amniotic fluid.
• Maximum Vertical Pocket: This test is used to check the volume of amniotic fluid in the thickest part of the uterus, which doesn’t include a fetal portion and umbilical cord. An ultrasound is performed to check this.
• Blood Tests: Blood tests like maternal serum screening can help in the detection of low amniotic fluid. It also allows the doctor to check if your baby has any congenital problems like Down’s Syndrome.
• Amniotic Wrinkle: If you are carrying identical twins, then you may have an amniotic wrinkle, which is caused by the folding of the inter-twin membrane. By checking the amniotic fluid properly, doctors can detect if both babies are getting enough amniotic fluid or not.

If any of the above assessments point at oligohydramnios, then a team of experts need to manage your pregnancy and delivery.

Risk Factors of Oligohydramnios

Some women are at a higher risk of oligohydramnios than others. Risk factors include the following:

• High blood pressure during pregnancy
• Diabetes
• Problems with placenta
• Lupus
• Obesity

If you are facing any of these issues in pregnancy, it is wise to get yourself checked for this pregnancy complication.

How Does Low Amniotic Fluid Affect Your Baby?

There are numerous and severe problems associated with low amniotic fluid if it is diagnosed during the first and second trimester. If the same is detected in the third trimester, then the situation can be brought under control as the doctors are well equipped for handling the complications at this stage. The problems associated with low amniotic fluid are as follows:

• Your baby may be born with severe congenital disabilities like missing internal or external organs or malformation of bones like dysplasia or clubfoot.
• It can also result in stillbirth or in-utero death of the baby after the 20th week of pregnancy. Some babies die soon after birth.
• Miscarriage after the 20th week is also one of the complications associated with low amniotic fluid.
• The baby may be born prematurely, before the 37th week, with low birth weight and underdeveloped organs.
• If oligohydramnios is diagnosed during the third trimester, when a baby may be born with limited growth, a compressed umbilical cord during labour, and may require caesarean delivery.

Oligohydramnios Complications

Some of the severe complications or oligohydramnios effects on the baby are listed below (7):

• Foetal compression syndrome
• Placental problems, such as abruption
• Amniotic band syndrome
• Pulmonary hypoplasia
• Severe foetal infection
• Facial and limb anomalies
• Miscarriage
• Poor fetal lung growth
• Poor fetal growth
• Stillbirth
• Preterm birth

These complications pose a significant risk to your pregnancy and can adversely affect the baby.

Treatments for Oligohydramnios

If decreased amniotic fluid is diagnosed in the third trimester, then the doctors are well equipped to handle it. Also, if the condition is mild, then it doesn’t require any treatment in the third trimester. The doctor will only prefer to keep you under observation for oligohydramnios management. But if oligohydramnios is diagnosed in the first or the second trimester, then the following treatments may be followed to deal with low amniotic fluid in your uterus.

• Amnioinfusion: According to the Mayo Clinic, this treatment involves the doctor infusing sodium chloride in your amniotic sac through an intrauterine catheter, at room temperature (8).
• Vesico-amniotic shunt: If the low amniotic fluid is due to your baby not being able to pass urine, then the doctor will try to divert your baby’s urine with the help of a vesico-amniotic shunt. While this procedure will take care of the low amniotic fluid in your uterus, it doesn’t ensure the effective functioning of your baby’s kidneys or lungs.
• Fluid Injections: This is a temporary method of treating oligohydramnios by injection fluid with the aid of amniocentesis.
• Maternal Hydration: Here, the doctor advises you to drink lots of water and put you in IV and oral fluids to increase the volume of amniotic fluid. This is applicable if the cause of oligohydramnios is dehydration.
• Bed rest: If you have mild oligohydramnios, then your doctor will keep you under observation and advise you complete bed rest. Proper hydration and complete bed rest can help to increase intravascular spaces, hence making more space for amniotic fluid.
• Termination of pregnancy: The worst of all may be the medical termination of pregnancy due to severe oligohydramnios during the first trimester. But it is the best for you and the baby as the baby may be born with severe and multiple defects.

Your doctor will usually involve a specialist in maternal foetal medicine to treat oligohydramnios. This is to deal with severe complications that may occur in your baby due to low amniotic fluid, like hydrops foetalis and congenital malformations.

How Can You Prevent Oligohydramnios?

Preventing oligohydramnios entirely is not possible, and a few precautions during pregnancy may reduce the chances of amniotic fluid becoming low during pregnancy.

• Drink a lot of water and keep yourself hydrated. Many cases of oligohydramnios are due to dehydration.
• Eat healthy food and listen to your doctor. Consult a nutritionist if necessary.
• Do not take any medicines without speaking to your doctor; not even herbal supplements or vitamins.
• Exercise regularly without exerting yourself. But walking periodically or prenatal yoga is beneficial during pregnancy.
• Stop smoking. It affects your baby’s lungs directly.
• Keep your prenatal check-up appointments without fail. Regular check-ups can help your doctor to determine any problems or abnormalities during pregnancy.

When to Consult a Doctor?

Pregnant women are advised to consult a doctor if they experience any of the following:

• Vaginal bleeding
• Leakage of amniotic fluid from the vagina
• Contractions
• Pelvic pain or cramps
• Low or very faint movement of the baby in the womb

FAQs

1. How do I know if I have low amniotic fluid during pregnancy?

Low amniotic fluid often has no obvious symptoms and is usually detected during an ultrasound. Fluid leaking from the vagina, measuring smaller than expected for your gestational age, or noticing reduced fetal movement may prompt further evaluation.

2. Can low amniotic fluid affect my baby?

It can increase the risk of complications, particularly when it develops earlier in pregnancy or is associated with another underlying problem. Possible concerns include umbilical cord compression, restricted fetal growth and the need for earlier delivery.

3. Can drinking more water increase amniotic fluid?

Increasing maternal fluid intake may raise amniotic fluid levels in some pregnancies, but it is not a guaranteed treatment. If your fluid is low, your healthcare provider will determine whether hydration, monitoring or another treatment is appropriate.

4. Does low amniotic fluid mean I will need an early delivery?

Not necessarily. The decision depends on factors such as how low the fluid is, your baby’s gestational age, fetal growth and overall well-being. Your healthcare provider may recommend additional monitoring and, when appropriate, delivery.

5. Can I expect low amniotic fluid at 32 weeks?

Yes, your doctor may suspect low amniotic fluid around 32 weeks if the movement of the fetus is very less or if you have leakage of amniotic fluid from your vagina. 

Oligohydramnios can be mild or severe. In both cases, your doctor would like to keep you under close supervision. Keep your appointments and consult your doctor in case of the slightest doubts. Be alert and watch your pregnancy carefully.

Also Read:

Leaking Amniotic Fluid
Watery Discharge during Pregnancy
Increase and Decrease Amniotic Fluid during Pregnancy

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Sources References

1. Cleveland Clinic – Oligohydramnios

2. March of Dimes – Oligohydramnios

3. Children’s Minnesota – Oligohydramnios treatment at Midwest Fetal Care Center

4. NHS – I have less amniotic fluid than expected in my pregnancy (Oligohydramnios)

5. American Pregnancy Association – Low Amniotic Fluid Levels: Oligohydramnios

6. Merck Manual – Oligohydramnios

7. Children’s Hospital Colorado – Oligohydramnios

8. Mayo Clinic – Low amniotic fluid: Can it be treated?