What Are Oligohydramnios and Polyhydramnios?

By April 4, 2018Obstetrics

Amniotic fluid is the protective liquid that surrounds your baby. It keeps the foetus safe and facilitates the exchange of nutrients between you two, so it’s very important for your baby’s growth and development.
Oligohydramnios and Polyhydramnios

Oligohydramnios and polyhydramnios are conditions where there is an abnormal amount of amniotic fluid in the womb. They can both be quite serious, so it’s important to be aware of the symptoms and what to do.

Oligohydramnios and polyhydramnios are two conditions characterised by abnormal levels of amniotic fluid – the former being too low and the latter being too high.

Polyhydramnios can be indicative of another condition or foetal anomaly, and oligohydramnios can result in poor foetal development and may be critical for your baby. Therefore they can both be quite serious issues.

What Does Amniotic Fluid Do?

Amniotic fluid is important for a number of reasons:

• It supports and protects your baby while inside the uterus, cushioning it in case you fall or suffer some kind of blow in your abdomen.

• It provides some room for your baby to move, helping with muscle and bone development.

• It contains important nutrients, hormones and antibodies that assist your baby’s growth and development.

In your second trimester, your baby begins to “breathe” the fluid, which is important for lung development.

• It keeps your baby warm and regulates temperature.

• It helps stave off infection.

• It helps keep the umbilical cord free from getting caught and becoming compressed, ensuring a constant flow of nutrients.


Oligohydramnios is suspected when there is less than 500mls of amniotic fluid is present in the uterus between the 32nd and 36th week of pregnancy. There aren’t many symptoms – the only real indicators are that you may notice less foetal movement, or you may not be as big as is normal for your level of gestation.

It is most common in the third trimester, but earlier too. It is also common in women who are past their due date as fluid levels can decrease after 42 weeks of gestation. This is because the placenta does not work as well after a baby reaches its due date. This problem with the placenta is one of the reasons why it is not a good idea to go too far past your due date.

Oligohydramnios may be caused by:

• A congenital abnormality in your baby

• Issues with your baby’s kidneys or urinary tract

• Placental issues

• A ruptured amniotic sac

• Chromosomal abnormalities in your baby

• Maternal problems, such as if your baby isn’t getting enough fluids or if you have a condition like pre-eclampsia, gestational diabetes, or kidney issues

Treatment of oligohydramnios will depend on the stage of your pregnancy. If you are in your second trimester, management techniques are necessary. This involves closely monitoring you and your baby and assessing an underlying cause. If you are close to full term, your obstetrician may suggest early delivery of your baby to be on the safe side.



Amniotic fluid is recycled in and out of your baby’s lungs and kidneys. This means that the levels are constantly fluctuating. If the levels do not fluctuate, a problem with the baby may be suspected as this may indicate some issue with your baby’s ability to absorb and excrete the fluid.

Polyhydramnios is quite rare and, in most cases, it causes no complications. However, it may increase the risk of:

• Premature rupture of the amniotic sac, causing premature birth

• Breech delivery

• Issues with your baby’s growth and development

• Cesarean section

• Placental abruption

• Umbilical cord prolapse

• Stillbirth

The signs and symptoms of polyhydramnios include increased abdominal size and discomfort, breathlessness, swelling of the legs and lower extremities, and a tense, taut abdomen. Again, treatment is usually focused on close management. In some cases, an amniocentesis (amniotic fluid test) may be required to drain away some of the excess fluid.

If you have any questions or concerns about your pregnancy or would like to book an appointment, please don’t hesitate to give us a call.

We will be more than happy to help and offer compassionate care in every way possible.