What is amniotic fluid? Its Functions & Disorders in Pregnancy.

There are a lot of things happening in your body during pregnancy, you may not know about all of them. Amniotic fluid is one such thing. It is a clear yellowish fluid that starts to form within the first 12 days of conception. It is present inside the amniotic sac surrounding the developing fetus in the uterus. Amniotic fluid is a very important component required for the development of a healthy fetus. However, if the amount is less or more than normal amniotic fluid, it can lead to complications.

In this article, we are going to discuss what amniotic fluid is? We will go through various functional aspects of it and will also discuss what happens when the amniotic fluid volume show variations?

What is amniotic fluid?

To understand what Amniotic fluid is, let us first discuss the position of the child inside the mother’s body. When your baby is in the womb, it is inside a sac-like structure called amniotic sac. It is a bag formed of two membranes, the amnion and the chorion respectively. This sac is surrounded by adequate amniotic fluid. The initial formation of this fluid is supported by the water from the mother’s body. By the end of the 20th week, it is almost entirely replaced by fetal urine. Amniotic fluid provides the child with vital components such as nutrients, hormones, and various antibodies. Generally, normal amniotic fluid volume is seen in pregnancy, but if the level of amniotic fluid shows variation, it can pose some serious complications.

A. Functions:

There are various functions of amniotic fluid, protection of the fetus being the most important. Let us discuss some of these works in detail:

  • Protection: This is the main function of amniotic fluid. It basically acts as a shock absorber, preventing any damage to your baby from outside pressure. 
  • Thermal stabilization: Amniotic fluid insulates the fetus, keeping it warm and maintaining a normal temperature.
  • Fights Infection: It protects the fetus from infections as it contains various antibodies.
  • Development of Muscles and Bones: The growing fetus floats in the amniotic sac which allows freedom of movement. It gives the bones and muscles the opportunity to develop properly.
  • Organ System development: The baby learns to use the muscles of the lungs and digestive systems by breathing and swallowing the amniotic fluid. 
  • Lubrication: If it were not for amniotic fluid, the fingers and toes would grow attached. Low amniotic fluid causes webbing of fingers and toes.
  • Protects umbilical cord: Amniotic fluid prevents compression of the umbilical cord and allows seamless transport of food and oxygen from the placenta to the growing fetus.
Human fetus inside womb

Generally, the amniotic fluid is at its highest level around the 36th week of pregnancy, measuring around 1 liter. This level reduces as labor comes closer. When labor begins, the amniotic sac ruptures and the fluid leaks out via cervix and vagina. This is termed as water breaking. 

Now that we know the various functions of it, let us discuss some disorders and complications related to elevated or reduced levels of amniotic fluid. 

B. Disorders:

The amount of amniotic fluid is different for each pregnancy. However, the amniotic fluid level needs to be monitored constantly. Any change in its level can result in abnormal fetal development. There are two major complications regarding amniotic fluid:

1) Oligohydramnios-

Lower levels of amniotic fluid than adequate amniotic fluid is referred to as Oligohydramnios. It is a rare condition occurring in 4% of all pregnancies. It is diagnosed when the Amniotic Fluid Index (AFI) has seen on ultrasound measures less than 5 cm whereas a normal index ranges between 5-25 cm.

The risk for mothers having complications or disorders before pregnancy increases significantly.

Here are some of the pregnancy complications that elevate the risk of oligohydramnios – 

  • Chronic Hypertension
  • Abrupt placenta
  • Preeclampsia
  • Diabetes
  • Twins or Triplets
  • Kidney disorders
  • Overdue pregnancy

Low amniotic fluid might occur during any trimester, but is a more serious concern during the first six months of pregnancy. During the first trimester, the chances of birth defects and loss of pregnancy are higher. Preterm birth and neonatal loss of life are some of the severe complications seen during the second trimester. During third trimester, the risk of labor complications increase ten folds if the mother has oligohydramnios. Cases of slow baby development are also seen during the third trimester.

During Oligohydramnios, prenatal care becomes very important. Maintain weekly appointments with your doctor to keep everything in check. When diagnosed, doctors may use some of the following tests:

  • Nonstress tests: This helps the doctor to check the baby’s heartbeat when it is resting and when it is moving. 
  • Biophysical profiling:  Biophysical profiling uses an ultrasound to detect movement of the fetus. It also allows the doctor to monitor baby’s muscle tone and breathing
  • Fetal kick counts: This is to time how long it takes for the baby to kick a certain number of times.

In certain cases, doctors plan to induce labor to prevent any harm to the child because  Oligohydramnios significantly increase the risk of umbilical cord compression, causing labor complications. In such cases, a cesarean delivery might become necessary. 

Pregnant woman holding a baby bear

2) Polyhydramnios-

When the amount of amniotic fluid is higher than normal amniotic fluid levels, it is called Polyhydramnios. It is found very rarely, 1% in all pregnancies to be exact. Polyhydramnios is confirmed when the AFI is more than 24cm and MVP is higher than 8cm. Polyhydramnios is mostly diagnosed during the third trimester. However, certain cases of second trimester polyhydramnios have also been seen. 

Here are some of the known causes of polyhydramnios:

  • gastrointestinal disorders such as atresia in the fetus.
  • Birth defects in the mother leading to irregular placentation  
  • Lack of red blood cells in the baby
  • Heart rate problems of the fetus
  • Blood mismatching between mother and child. 
  • Rh incompatibility
  • Excessive amniotic fluid can also be formed in multiple pregnancy. 

There are certain problems faced by mothers if they have Polyhydramnios, which act as symptoms. They are:

  • Mothers report swelling in stomach which occurs due to enlargement of the uterus caused by excessive amniotic fluid. 
  • Difficulty in breathing and abdominal pain are also seen in mothers with polyhydramnios.

Other complications related to Polyhydramnios are:

  • Premature Labor
  • Premature Preterm Rupture Of Membranes [PPROM]
  • Ruptured Placenta
  • Fetal Demise
  • Postpartum Hemorrhage

The above-mentioned are some of the complications due to polyhydramnios. In mild cases, the amount of amniotic fluid reduces on its own. But, when amniotic fluid reaches its threshold, the situation becomes severe and needs to be taken care of instantly. In such cases, amniocentesis is performed by the doctor to reduce the amount of amniotic fluid inside the mother’s uterus. Certain medications such as indomethacin also help in the reduction of amniotic fluid. They reduce the amount of urine produced by the baby. 

Polyhydramnios is also found to be a major cause of bleeding during pregnancy

Effects of Polyhydramnios on the fetus:

  • It can cause various bone disorders
  • It can cause neural and brain damage
  • The pressure can lead to reduced lung growth causing breathing issues. 
  • It can cause narrowing of major blood vessels. 
Development of an embryo inside the uterus

Amniotic fluid is a very important component for the proper development of your child. Amniotic fluid needs to be maintained and for this, there are various methods that you can keep in mind such as:

  • Maintain a healthy diet and add fruits with high water content. Also, try to increase your water intake as it helps in maintaining amniotic fluid levels.
  • Healthy lifestyle is a perfect way to have a healthy pregnancy.
  • Exercises can help you maintain your amniotic fluid level.
  • Maintain weekly visits to your prenatal caretaker.

FAQs about Amniotic Fluid:

1. What is amniocentesis and can it reduce excessive amniotic fluid?

Amniocentesis is a medical procedure in which a small sample of amniotic fluid from the mother’s womb is taken for laboratory testing. It is basically a prenatal diagnosis for sex determination which is illegal in India. However, amniocentesis can be very helpful in Polyhydramnios. It can be used to drain all the excessive amniotic fluid out of the mother’s womb.

2. How to increase Amniotic fluid volume?

There are various methods that can help you to reduce Amniotic fluid, such as:

  • Drinking water is very helpful because the beginning amniotic fluid is made of water from mother’s body. 
  • Stop drinking alcohol as it dehydrates the body and also causes the thickening of amniotic fluid, which can be dangerous for your baby. 
  • Regular workout helps your body to circulate the blood better. This increases the blood flow in the uterus and increases the amount of amniotic fluid.

3. Do unborn babies drink amniotic fluid?

Yes, babies ingest amniotic fluid. Amniotic fluid is 98% water and 2% salts. It helps the fetus to learn the use of digestive system muscles. It also develops the kidney muscles of the fetus.

4. How much amniotic fluid is adequate? 

Around 600 ml of amniotic fluid is seen at full term in normal pregnancies. Amniotic fluid is highest during 34th week which is around 800-850 ml. So amniotic fluid between 550 ml and 650 ml is considered adequate.

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