The amount of amniotic fluid is greatest at about 34 weeks when it averages 800 mL. About 600 mL of amniotic fluid surrounds the baby at full term (40 weeks).
The amniotic fluid constantly moves (circulates) as the baby swallows and "inhales" the fluid, and then releases it.
So what happens if there is not enough amniotic fluid? Is it dangerous for your baby and how does if affect your pregnancy?
Low amniotic fluid is a condition in which the amniotic fluid measures lower than expected for a baby's gestational age. The amount of amniotic fluid is a measure of your baby’s well being because it reflects the baby's urine output.
After around 20 weeks of pregnancy, your unborn babies' kidneys produce most of the amniotic fluid, so low levels can be caused by kidney problems. The medical term for low amniotic fluid is oligohydramnios.
Approximately 4% of women will be diagnosed with low amniotic fluid levels (oligohydramnios) during pregnancy. It can happen at any time during pregnancy, but it's most common in the last 3 months. If you have a healthy pregnancy and get oligohydramnios near the end of your pregnancy, you probably don't need treatment.
Your doctor or midwife will monitor you more closely and may do weekly ultrasounds to monitor the level of fluid.
If the level gets too low or affects the ability of your placenta to function, they may recommend an induction of labour. If you are diagnosed with low amniotic fluid levels, it's essential to know if there is an underlying cause before agreeing to management.
An induction of labour for low fluid levels at full term in a healthy pregnancy is associated with higher levels of interventions and possible adverse outcomes for mothers and babies. It's important you are provided with all the necessary information to make an informed decision about your care.
Amniotic fluid is necessary for normal growth and development of your baby so low levels can cause Intra Uterine Growth Retardation or IUGR if it occurs in early pregnancy.
While it's rare to get oligohydramnios in the first half of pregnancy, it's associated with several complications including premature labour and miscarriage.
Low fluid levels can cause compression of the baby's organs and limbs, resulting in birth defects like hip dysplasia and club foot.
Since low amniotic fluid may be caused by underlying conditions such as high blood pressure or diabetes, treating these conditions may improve your levels.
This may involve taking medication, monitoring your blood sugar, or making more frequent visits to your doctor. The amount of amniotic fluid is measured during ultrasound scans. In a normal pregnancy you will usually have at least 3 or 4 scans and the amniotic fluid levels will be measured each time.
There are two ways to measure the fluid: amniotic fluid index (AFI) and maximum vertical pocket (MPV). Both are measured in centimeters (cm).
A normal amniotic fluid index is 5cm to 25cm using the standard assessment method. Before 24 weeks or in pregnancy with multiples, amniotic fluid is measured via ultrasound with a method called the "maximum vertical pocket."
The ultrasound technician will scan your uterus to find and measure the single deepest pocket of amniotic fluid they can. A normal measurement is 2cm to 8cm.
A finding of less than 2cm indicates low amniotic fluid at this stage. The AFI checks how deep the amniotic fluid is in four areas of your uterus. These amounts are then added up. If your AFI is less than 5cm, you have oligohydramnios.
Staying well hydrated during pregnancy is important, even if your levels are normal and even better if you can supplement daily with coconut water as it contains valuable minerals and electrolytes.
According to one study hydration is very helpful for increasing amniotic fluid levels between 37 and 41 weeks of pregnancy.
Regular prenatal appointments are essential to monitor your overall healthy, including amniotic fluid levels. If you're at all concerned, it's always best to give your doctor a call.
Some signs that warrant an immediate call to your doctor include feeling your baby move less than usual or fluid leaking from your vagina.
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