Low Amniotic Fluid (Oligohydramnios) during Pregnancy

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Low Amniotic Fluid during Pregnancy

Amniotic fluid is a water-like fluid that helps in the development of the baby. It performs a lot of crucial functions that are important in keeping your baby safe while it grows in your womb, and in its proper development. Let us find out more about amniotic fluid and the causes behind the amniotic fluid becoming low in pregnant women.

What is Amniotic Fluid?

Your baby grows and develops inside a fluid-filled bag called the amniotic sac. This amniotic sac is filled with amniotic fluid. Amniotic fluid cushions your baby and protects it from all sorts of infections. It also protects your baby from getting hurt if you suffer a blow to your tummy. It keeps the temperature inside the womb constant and also helps in the development of baby’s muscles, limbs, lungs and digestive system.

Developing embryo in uterusAs your baby begins to breathe in the second trimester, she will start swallowing the amniotic fluid and later pass it as urine. That’s how a baby maintains the volume of amniotic fluid around herself.

What is Oligohydramnios?

Oligohydramnios is a condition where the volume of amniotic fluid inside the amniotic sac is too low. 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 are high chances of your amniotic fluid becoming low. 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 has several functions as follows:

  • 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 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 constant.
  • 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 till the 36th week of pregnancy, and it measures anywhere between 800 to 1000 ml which are considered normal. After the 36th week 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 gestation or at full term, and that too is normal.

Common 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 is the first 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 Low Amniotic Fluid

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

  • 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 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 abnormality. This becomes obvious in the scan if your baby is passing very less 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 pre-eclampsia, then your placenta may fail to supply enough blood and nutrition to your baby. In this case, the volume of amniotic fluid in your baby may fall, and you may have to be under strict supervision.
  • Medication: Some medicines must be avoided during pregnancy as they cause low amniotic fluid. Especially drug for high blood pressure and 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.

Woman pregnant with twins

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

Following methods can be used to detect oligohydramniosis.

  • Ultrasound: The best and first diagnosis for oligohydramnios is an ultrasound scan. During the ultrasound, the amniotic fluid volume is measured in four various parts of your uterus, and then all the four values are put together to regulate the amniotic fluid index or the 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 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 doctors to check for a range of motion which is caused due to 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. Once again, ultrasound is used to conduct this test.
  • 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 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 line 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 other. 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 the low amniotic fluid.
  • Babies are 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, compressed umbilical cord during labour, and caesarean delivery.

Complications of Low Amniotic Fluid

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

  • Foetal compression syndrome
  • Amniotic band syndrome
  • Pulmonary hypoplasia
  • Severe foetal infection

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

Treatments for Oligohydramnios

If oligohydramnios 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: In this treatment, the doctor infuses sodium chloride in your amniotic sac through an intrauterine catheter, at room temperature.
  • 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 vesico-amniotic shunt. While this procedure will take care of the low amniotic fluid in your uterus, but it doesn’t ensure the effective functioning of your baby’s kidney 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 dehydration causes oligohydramnios.
  • 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.

Pregnant woman restingHow Can You Prevent Oligohydramnios?

Preventing oligohydramnios entirely is not possible, and 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. Only regular check-up and help your doctor to determine any problem or abnormalities during pregnancy.

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: Preeclampsia in Pregnancy

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