If your pregnancy has flown past your due date, you’re probably very ready for your baby to make his big debut. And your baby may be, too — especially if you have low amniotic fluid, or oligohydramnios. Here’s what you need to know about this relatively common pregnancy condition, including causes and treatments.

What does it mean when you have low amniotic fluid during pregnancy?

Oligohydramnios is a condition during pregnancy where there’s lower-than-expected amniotic fluid surrounding a baby for his gestational age. 

Throughout pregnancy, your amniotic fluid cushions your baby and allows him to grow and move. It also keeps your baby’s body from compressing the umbilical cord against the uterine wall. Sometimes, amniotic fluid levels can signal how well your baby’s urinary system is working, since a baby excretes urine into the amniotic fluid.

Symptoms of low amniotic fluid when you’re pregnant

The main symptoms of low amniotic fluid aren't obvious to expecting moms — which is why it’s so important to make sure you hit all of your scheduled prenatal checkups. If you have low amniotic fluid, your doctor may note:

  • Your uterus measures smaller than anticipated for your baby's gestational age
  • You’re not gaining enough pregnancy weight
  • Your baby’s heart rate goes down for several seconds suddenly before returning to normal 
  • You have a decreased amount of amniotic fluid, which is detected via ultrasound

Occasionally, you may notice:

  • A significant decrease in fetal activity
  • Fluid leaking from your vagina

What causes low amniotic fluid during pregnancy?

Low amniotic fluid can result from your water breaking, from a puncture in the amniotic sac after amniocentesis or from a spontaneous fluid leak at any point during pregnancy that’s so small it may go unnoticed.

More rarely, oligohydramnios is linked to:

  • Problems with baby's kidneys or urinary tract, since low amniotic fluid levels could signal a baby might not be peeing as much as expected
  • Poor fetal growth
  • Placental abruption (the early separation of the placenta, which provides baby with nutrients and oxygen, from the uterine wall during pregnancy)
  • Chronic high blood pressure or preexisting diabetes in Mom
  • Certain medications, including those that manage high blood pressure
  • Birth defects
  • Premature rupture of membranes (PROM)

Who's most at risk and how common is it?

Women whose pregnancies are post-term (i.e. those who are 42 weeks pregnant) are most at risk of low amniotic fluid. An estimated 4 percent of pregnant women are diagnosed with oligohydramnios, and that rate rises to 12 percent among overdue women since amniotic fluid levels tend to decrease late in pregnancy.

When does it usually happen? 

Low amniotic fluid usually develops in the latter part of the third trimester, although it can happen earlier in pregnancy.

What effect does it have on the baby?

Most women diagnosed with low amniotic fluid in the third trimester will have a completely normal pregnancy. If there are very low levels of amniotic fluid for your baby to float around in, there is a slight risk of intrauterine growth restriction and umbilical cord constriction during birth. You may also be more likely to have a C-section.

If your doctor detects low amniotic fluid in the first or second trimesters, the risks are greater and may include miscarriage, premature birth, birth defects or stillbirth.

Remedies for low amniotic fluid

No remedies have been proven to raise low amniotic fluid in the long-term. But if you are diagnosed with oligohydramnios, there are steps you can take to boost your amniotic fluid levels in the short-term. Your doctor may recommend:

  • Getting a lot of rest and possibly less physical activity
  • Drinking plenty of water
  • Continued close monitoring of your amniotic fluid levels, which may include nonstress testing or biophysical profile
  • An early or scheduled delivery if low amniotic fluid endangers the well-being of your baby, especially if you’re at least 36 weeks pregnant
  • A transfusion of saline solution (salt water) into the uterine cavity using a catheter placed in the cervix to replace lost or low levels of amniotic fluid, which is known as an amnioinfusion and is typically done during labor
  • Fetal surgery, if low amniotic fluid is linked to a problem with your baby’s urinary tract and surgery can correct it

Can you prevent low amniotic fluid?

While there’s no way to prevent oligohydramnios, it’s important to work with your doctor to manage your medications and any conditions linked to low amniotic fluid, including diabetes and high blood pressure. Regular checkups allow your practitioner to measure your abdomen and make sure there’s enough amniotic fluid for your baby to develop properly.

If your doctor is concerned that your amniotic fluids might be low, he or she may recommend an ultrasound to measure the volume of fluid in the amniotic sac.

Low amniotic fluid can be a serious condition, which is why it’s essential to keep up with your prenatal appointments. The good news is that most women who are diagnosed with low amniotic fluid have perfectly healthy pregnancies.