Low Amniotic Fluid

Low Amniotic Fluid


What is amniotic fluid?     Pregnancy and Asthma

In this blog I am going to cover Oligohydraminos also known as low amniotic fluid.

Amniotic fluid fills the around your baby sac around your baby and plays a vital role in protecting your baby:

  • It acts as a cushion to protect your baby from trauma for example if you have a fall.
  • It prevents the umbilical cord from becoming compressed which would reduce the oxygen supply to your baby.
  • It helps to maintain a constant temperature in the womb.
  • It protects against infection.
  • It helps the digestive and respiratory system develop.
  • It allows your baby to move around so that his muscles and bones develop properly.

Where does the amniotic fluid come from?

During the first 14 weeks of your pregnancy, fluid passes from your circulatory system into the amniotic sac. Early in the 2nd trimester, your baby starts to swallow the fluid, pass it through his kidneys and excrete it as urine which he then swallows again. Recycling the volume of amniotic fluid every few hours.

Your baby plays an important role in keeping the correct volume of fluid in the amniotic sac. Sometimes this does not happen resulting in too much or too little fluid and both situations can present problems.


How much amniotic fluid should I have?

The amount of amniotic fluid varies but continues to increase up to the 3rd trimester. It tends to peat at 34-36 weeks and then it gradually decreases until you give birth. When there is too little fluid at any point in your pregnancy it is called oligohydramnios. Where there is too much it is called polyhydramnios.


How will I know if the level of amniotic fluid is too low?

Your doctor or midwife may suspect this problem if

  • You are leaking fluid,
  • measuring small for dates,
  • or not feeling your baby move very much.
  • They will also monitor for it if:
  • you previously had a small for dates baby
  • if you have high blood pressure / preeclampsia
  • diabetes
  • Or past your dates.

To find out what is happening your doctor or midwife will send you for an ultrasound examination. The sonographer will measure the largest pockets of fluid in 4 different sections of your uterus and add them together to see where you rate on the amniotic fluid index (AFI) This measurement will confirm whether you have low levels or not.


What could be causing the problem?

Experts don’t always know what causes low levels of amniotic fluid. It is more common late in the 3rd trimester, more so if you are past your due date. The later in pregnancy the condition happens the better the outlook for your baby.

The following are some causes:

  • Leaking amniotic fluid or ruptured membranes (waters broken)
  • Sometimes a small tear in the amniotic membranes (sac containing baby) can allow some fluid to leak out. This can happen at any time in your pregnancy but it is more common towards the end of pregnancy approaching labour. If you find that your underwear is continuously wet please let your midwife or doctor know.
  • If your membranes have ruptured there is an increased risk of infection for both you and your baby, because it provides a way for bacteria to enter the amniotic sac. Sometimes a very small tear can heal over, the leaking of fluid will stop and the fluid level will return to normal.
  • Placenta Problems. A problem with your placenta for example a small abruption (bleed) where the placenta peels away from the wall of the uterus and this can lead to low levels of amniotic fluid. If the placenta does not supply enough blood and nutrients to your baby, your baby may stop producing urine
  • Some medical conditions: High Blood Pressure, Preeclampsia and Diabetes can result in low amniotic fluid levels.
  • Multiple Pregnancy If you are pregnant with twins or triplets you are at risk of low fluid levels around the babies. Oligohydraminos is likely in the case of twin to twin transfusion syndrome in which case one twin has too little amniotic fluid and the other twin has too much.
  • Fetal Abnormalities. If your doctor or midwife finds low levels of amniotic fluid in the first or second trimester it may be there is a problem with baby. For example the baby’s kidneys may not have developed properly and the baby’s urinary tract is blocked so the baby can’t produce enough urine to maintain the level of amniotic fluid.

What will happen if I have oligohydramnios?

If you have low levels of amniotic fluid your doctor will monitor your pregnancy very closely to make sure your baby continues to grow normally. Management of your pregnancy will depend on how far on you are in your pregnancy, how your baby is doing and whether you have other complications.

If you are near your date, your doctor will probably bring you in to hospital for induction (start your labour).

If you have severe preeclampsia or your baby is not growing you may need to have your baby early.

Your baby will be monitored very closely with frequent ultrasound scans, Doppler studies and CTG trace of baby’s heart beat.

You will be asked to drink plenty of fluids, do a kick chart where you will count baby movements and advised to alert your midwife or doctor if you notice movements are becoming less.

Low levels of amniotic fluid can make complications during labor more likely. The main concern is that the fluid level will get so low that your baby’s movements or your contractions will compress the umbilical cord.

During labor, your practitioner may pass a flexible catheter through your cervix so that she can pump a steady stream of warm saline solution into the amniotic sac to reduce the risk to the cord. If your baby can’t safely tolerate labor, your doctor or midwife will recommend a C-Section.


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