Low amniotic fluid
The amniotic fluid is part of the baby’s life support system. It protects your baby and aids in
the development of muscles, limbs, lungs and digestive system. Amniotic fluid is produced soon after the amniotic
sac forms at about 12 days after conception. 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
What is oligohydramnios?
Oligohydramnios is the condition of having too little amniotic fluid. Doctors can measure the
amount of fluid through a few different methods, most commonly through amniotic fluid index (AFI) evaluation or
deep pocket measurements. 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. About 8% of pregnant women can have low levels
of amniotic fluid, with about 4% being diagnosed with oligohydramnios. 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.
Oligohydramnios can cause complications in about 12% of pregnancies that go past 41 weeks.
What causes low amniotic fluid?
Birth defects – Problems with the development of the kidneys or urinary tract
which could cause little urine production, leading to low levels of amniotic fluid.
Placental problems – If the placenta is not providing enough blood and
nutrients to the baby, then the baby may stop recycling fluid.
Leaking or rupture of membranes –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.
Post Date Pregnancy- 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.
Maternal Complications- Factors such as maternal dehydration, hypertension,
preeclampsia diabetes, and chronic hypoxia can have an effect on amniotic fluid levels.
What are the risks of having low amniotic fluid?
The risks associated with oligohydramnios often depend on the gestation of the pregnancy. The
amniotic fluid is essential for the development of muscles, limbs, lungs, and the digestive system. In the second
trimester, the baby begins to breathe and swallow the fluid to help their lungs grow and mature. The amniotic fluid
also helps the baby develop muscles and limbs by providing plenty of room to move around. If oligohydramnios is
detected in the first half of pregnancy, the complications can be more serious and include:
If oligohydramnios is detected in the second half of pregnancy, complications can include:
Intrauterine Growth Restriction (IUGR)
Labor complications such as cord compression, meconium stained fluid and cesarean delivery
What treatments are available if I am experiencing low amniotic
The treatment for low levels of amniotic fluid is based on gestational age. If you are not full
tem yet, your doctor will monitor you and your levels very closely. Tests such as non-stress and contraction stress
test may be done to monitor your baby’s activity. If you are close to full term, then delivery is usually what most
doctors 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
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 doctors visualize
fetal anatomy and make a diagnosis.
Maternal re-hydration with oral fluids or IV fluids has shown to help increase amniotic fluid levels.