If you would like to learn more about amniotic fluid, go to Low Amniotic Fluid Volume.
Oligohydramnios, or low amniotic fluid volume, is a pregnancy complication that usually occurs during the last trimester, and is a pregnancy anomaly that involves an insufficient quantity of amniotic fluid for the stage of pregnancy. Commonly, oligohydramnios is referred to when the volume of amniotic fluid is lower than 500 ml (usually 1000 ml), or 50% of the average amount based on pregnancy age.
According to the different sources I consulted, some state that from 0.4-4% of women will face this situation. Other sources state that it is up to 8% of pregnancies.
Why do some women have less amniotic fluid during their pregnancy? There are several possible causes of this issue:
Causes of lack of amniotic fluid during pregnancy
The potential causes are multiple and they can accumulate or be unique.
For the baby:
- Fetal malformation
- Defective fetal renal function (balance between urine and hydration)
- Growth delays
- A placenta that detaches or ages, which harms exchanges and balance
For the mother:
- A crack in the amniotic sac
- Taking certain medications
- Gestational hypertension
- Postmaturity (beyond 41-42 weeks)
- Identical twins with a single placenta
To read about diagnosing oligohydramnios, read the next article How is Oligohydramnios Diagnosed?