Oligohydramnios

What is oligohydramnios?

Oligohydramnios is a condition during pregnancy when your amniotic fluid is lower than it should be. Amniotic fluid is a water-like fluid that surrounds a fetus during pregnancy. It protects it from infection and umbilical cord compression and cushions their movements. Amniotic fluid also helps develop a fetus’ digestive and respiratory system, as well as regulate its temperature.

Too little amniotic fluid can cause health issues in the fetus or be a sign of an underlying problem in the pregnancy. These conditions could affect fetal development or cause complications during labor and delivery.

Often, you don’t know your amniotic fluid is low. This is typically detected on ultrasounds being done for other reasons, like measuring a fetus’ growth. It can come as a surprise, and you may find yourself worried about how this will affect your pregnancy. Try not to panic. Most people with low amniotic fluid will deliver healthy babies. Treatment depends on how far along you are in pregnancy and if you have other pregnancy complications.

How common is it?

Low amniotic fluid affects about 4% of women during pregnancy. It’s most common in the last three months of pregnancy (third trimester). This rate rises to about 12% if you go past your due date because amniotic fluid levels tend to decline to low levels past that point.

How much amniotic fluid should I have during pregnancy?

It depends on how many weeks pregnant you are. You begin making amniotic fluid about 12 days after conception. Early in pregnancy, the amniotic fluid comes from the placenta. Starting at around 15 weeks, the amniotic fluid is pee from the fetus. The amount of amniotic fluid you produce increases until its peak at 36 weeks of pregnancy. After that, your levels of amniotic fluid start slowly decreasing. The amount of fluid in your uterus at any time will fluctuate as the fetus drinks the fluid and produces more pee.

What are the signs of low amniotic fluid?

You may not know you have low amniotic fluid. However, your healthcare provider may suspect it if:

• You’re leaking fluid from your vagina
• Your uterus measures small for how far along you are in pregnancy
• You don’t feel the fetus move enough

What causes oligohydramnios?

Often, the cause of low amniotic fluid is unknown. It can happen randomly in a healthy pregnancy. But other times, your healthcare provider can link low amniotic fluid to a specific cause.

Some possible causes of oligohydramnios are:

• Congenital anomalies that affect how the fetus’ kidneys or urinary tract are developing
• Problems with the placenta
• Going more than two weeks past your due date
• Hypertension or preeclampsia
• Dehydration
• Premature rupture of the membranes (PROM)

Having any of the above conditions or risk factors can make you more likely to have low amniotic fluid levels. You’re also at higher risk for low amniotic fluid if you’ve had low amniotic fluid in prior pregnancies.

What are the complications of oligohydramnios?

Low amniotic fluid in the first six months of pregnancy is generally more dangerous. These complications could include:

• Problems with organ development, such as underdevelopment of the lung tissue or deformities to the fetus’ limbs from being compressed in your uterus
• Preterm birth
• Stillbirth
• Infection if your water has broken early

If you receive an oligohydramnios diagnosis in the last trimester (weeks 28 to 40) of pregnancy, complications could include:

• Umbilical cord compression (twhen the umbilical cord is squeezed, preventing nutrition and oxygen from reaching the fetus)
• Fetal growth restriction
• Increased risk of C-section delivery
• Need for an early delivery
• Increased risk for infection if your water breaks too early

How is oligohydramnios diagnosed?

Your pregnancy care provider measures the amount of amniotic fluid in your uterus a few times during pregnancy using an ultrasound. If the amount of fluid is less than the recommended amount for the gestational age of the fetus, you may have oligohydramnios.

There are two ways to measure amniotic fluid: amniotic fluid index (AFI) and maximum vertical pocket (MVP).

• Amniotic fluid index (AFI) involves dividing your uterus into four sections and measuring the deepest pocket in each section. The four measurements are added together to get the AFI. Normal AFI is greater than 5 centimeters (cm).
• Maximum vertical pocket (MVP) involves measuring the single deepest pocket of amniotic fluid. The MVP should be less than 2 cm.

How is oligohydramnios treated?

It depends on how far along you are in your pregnancy and if you have other pregnancy complications. If you’re close to full term (37 weeks of pregnancy), your healthcare provider may decide that inducing labor is the safest option for your baby.

Your healthcare provider will schedule extra prenatal visits to monitor you closely and make sure the fetus is growing. These visits could include:

• Ultrasounds
• Nonstress tests

Other treatment options depend on the cause of the oligohydramnios. If there is concern for ruptured membranes or if the fluid is persistently low, you may need to go to the hospital for close monitoring.

Can drinking water increase amniotic fluid?

Maybe. Some studies show that drinking water can help increase amniotic fluid levels in women who are pregnant.

How can I prevent oligohydramnios?

There isn't anything you can do to prevent oligohydramnios. Attend all prenatal check-ups and be upfront with your healthcare provider about your symptoms and medical history. Knowing if you’re at risk for low amniotic fluid is your best chance for diagnosing and treating the condition.

Can a baby survive oligohydramnios?

Yes, your baby will likely be born healthy. Low amniotic fluid can be serious, but in most cases, babies do well after birth.

When should I see my healthcare provider?

Call your healthcare provider if you experience any of the following:

• Leaking amniotic fluid from your vagina (contact your provider if you’re unsure what kind of fluid you’re leaking)
• Vaginal bleeding
• Cramps or pelvic pain
• Contractions
• Feeling the fetus move less