Oligohydramnios: Causes, Symptoms, Diagnosis & Prevention
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. Additionally, 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.
Understanding Amniotic Fluid Levels
How much amniotic fluid you should have 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.
The following table illustrates the prevalence of low amniotic fluid based on the stage of pregnancy:
| Pregnancy Stage | Estimated Prevalence |
|---|---|
| During pregnancy (general) | 4% |
| Past due date | 12% |
Signs and Symptoms
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. 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.
Common Causes of 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.
Diagnosis and Management
Your healthcare provider diagnoses low amniotic fluid using an ultrasound. Treatment depends on how far along you are in pregnancy and how low your amniotic fluid is. It also depends on if you have other pregnancy complications. Most people with low amniotic fluid will deliver healthy babies, so it is important to try not to panic.
Potential Complications
Low amniotic fluid can cause pregnancy complications. These conditions could affect fetal development or cause complications during labor and delivery. 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 (when the umbilical cord is squeezed, preventing nutrition and oxygen from reaching the fetus).
- Fetal growth restriction.