Amniotic fluid protects your baby and aids in the development of muscles, limbs, lungs and digestive system. It is first made up of water that is provided by the mother, and then around 20 weeks fetal urine becomes the primary substance. As the baby grows he or she will move and tumble in the womb with the help of the amniotic fluid. In the second trimester, the baby will begin to breathe and swallow the amniotic fluid. In some cases the amniotic fluid may measure too low or too high. If the measurement of amniotic fluid is too low it is called oligohydramnios. If the measurement of amniotic fluid is too high it is called polyhydramnios.

What is oligohydramnios?

Oligohydramnios is the condition of having too little amniotic fluid. The fluid level is measured through a few different methods, most commonly through amniotic fluid index (AFI) evaluation. If an AFI shows a fluid level of less than 5 centimeters (or less than the 5th percentile), the absence of a fluid pocket 2-3 cm in depth, or a fluid volume of less than 500mL at 32-36 weeks gestation, then a diagnosis of oligohydramnios would be suspected. It can occur at any time during pregnancy, but it is most common during the last trimester. If a woman is past her due date by two weeks or more, she may be at risk for low amniotic fluid levels since fluids can decrease by half once she reaches 42 weeks gestation.

Causes:

  • Problems with the development of the kidneys or urinary tract which could cause little urine production, leading to low levels of amniotic fluid.
  • If problems arise with the placenta and it is not providing enough blood and nutrients to the baby, then the baby may stop recycling fluid.
  • Rupture of membranes or loss of fluid. This may be a gush of fluid or a slow constant trickle of fluid. This is due to a tear in the membrane. Premature rupture of membranes (PROM) can also result in low amniotic fluid levels.
  • A post date pregnancy (one that goes over 42 weeks) can have low levels of amniotic fluid, which could be a result of declining placental function.
  • Factors such as maternal dehydration, hypertension, preeclampsia, diabetes, and chronic hypoxia can have an effect on amniotic fluid levels.

Treatments:

The treatment for low levels of amniotic fluid is based on gestational age. If you are not full term yet, your provider will monitor you and your levels very closely. Tests such as non-stress test may be done to monitor your baby’s activity. If you are close to full term, then delivery is usually what most providers recommend in situations of low amniotic fluid levels. Other treatments that may be used include:

  • Amnio-infusion during labor through an intrauterine catheter. This added fluid helps with padding around the umbilical cord during delivery and is reported to help lower the chances of a cesarean delivery.
  • Injection of fluid prior to delivery through amniocentesis. The condition of oligohydramnios is reported to often return within one week of this procedure, but it can aid in helping providers visualize fetal anatomy and make a diagnosis.
  • Maternal re-hydration with oral fluids or IV fluids has shown to help increase amniotic fluid levels.