What does amniotic fluid do?

Amniotic fluid has several important functions:

•  Provides a cushion to protect the child from trauma (should you fall).
• Keeps the umbilical cord from becoming compressed and reducing the oxygen supply to your baby.
• Keeps the child moving so that bones develop correctly.
• Prevents infection, and helps to keep a regulated temperature in the womb.

The amount of amniotic fluid is measured either by checking the largest pocket of fluid by ultrasound or by measuring the largest amniotic fluid pocket in each of four quadrants and then adding those up. This is called the AFI or Amniotic Fluid Index.

* Normal AFV (amniotic fluid values) in the 2nd half of pregnancy implies at least one functioning fetal kidney.

What is too much or too little amniotic fluid?

The AFI and the single pocket evaluation are 2 ways to evaluate the amniotic fluid.

Polyhydramnios = Too much fluid (usually 25+ cm AFI)

Oligohydramnios = Too little fluid (AFI under 5 cm and/or no pocket over 2 cm)

Because the AFI has too many "false positive" results (too many people diagnosed with too low fluid when in fact the outcome was OK), the single pocket amniotic fluid evaluation has recently been found more reliable than the AFI. Any single pocket that's over 2 cm is considered adequate.

What is the treatment for too little or too much amniotic fluid?

Your doctor will perform an ultrasound to confirm the presence of an excess or lack of amniotic fluid to find out where you rate on the amniotic fluid index (AFI). Anything more than 25 cm is too much amniotic fluid, and anything less than 5 cm during the third trimester is too low. 

If you have too much fluid, you will likely have an amniocentesis to test for abnormalities and genetic issues. Testing for gestational diabetes will likely be done, and you will undergo regular ultrasounds and stress tests to monitor the condition of your baby. If you have too little fluid, you will be closely monitored until delivery.