Pregnancy complications

• Pregnancy complications may need special medical care.
• Common problems include anemia, diabetes and bleeding.
• Ask your provider about the signs of serious complications.

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Oligohydramnios is when you have too little amniotic fluid. Amniotic fluid is the fluid that surrounds your baby in your uterus (womb). It’s very important for your baby’s development.

How do you know if you have oligohydramnios?
If you notice that you are leaking fluid from your vagina, tell your health care provider. It may be a sign of oligohydramnios. Your provider watches out for other signs, such as if you’re not gaining enough weight or if the baby isn’t growing as fast as he should.

Your health care provider uses ultrasound to measure the amount of amniotic fluid. There are two ways to measure the fluid: amniotic fluid index (AFI) and maximum vertical pocket (MPV).

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 5 centimeters, you have oligohydramnios.

The MPV measures the deepest area of your uterus to check the amniotic fluid level. If your MPV is less than 2 centimeters, you have oligohydramnios.

Ask your health provider if you have questions about these measurements.

What problems can oligohydramnios cause?
If oligohydramnios happens in the first 2 trimesters (first 6 months) of pregnancy, it is more likely to cause serious problems than if it happens in the last trimester. These problems can be:

• Birth defects – Problems with a baby’s body that are present at birth
• Miscarriage – When a baby dies in the womb before 20 weeks of pregnancy
• Premature birth – Birth before 37 completed weeks of pregnancy 
• Stillbirth – When a baby dies in the womb after 20 weeks of pregnancy

If oligohydramnios happens in the third trimester of pregnancy, it can cause:

• The baby to grow slowly
• Problems during labor and birth, such as the umbilical cord being squeezed. The umbilical cord carries food and oxygen from the placenta to the baby. If it’s squeezed, the baby doesn’t get enough food and oxygen.
• A greater chance of needing a cesarean section (when your baby is born through a cut the doctor makes in your belly and uterus) 

What causes oligohydramnios?
Sometimes the causes of oligohydramnios are not known. Some known causes are:

• Health problems, such as high blood pressure or preexisting diabetes (having too much sugar in the blood before pregnancy)
• Certain medications, like those used to treat high blood pressure – If you have high blood pressure, talk to your provider before getting pregnant to make sure your blood pressure is under control.
• Post-term pregnancy – A pregnancy that goes 2 or more weeks past the due date. A full-term pregnancy is one that lasts 39 to 41 weeks.
• Birth defects, especially ones that affect the baby’s kidneys and urinary tract. 
• Premature rupture of the membranes (PROM) – When the amniotic sac breaks after 37 weeks of pregnancy but before labor starts.

How is oligohydramnios treated?
If you have a healthy pregnancy and get oligohydramnios near the end of your pregnancy, you probably don’t need treatment. Your provider may want to see you more often. She may want to do ultrasounds weekly or more often to check the amount of amniotic fluid.

Sometimes amnioinfusion can help prevent problems in the baby. Amnioinfusion is when the provider puts a saline solution (salty water) into the uterus through your cervix (the opening to the uterus that sits at the top of your vagina). This treatment can help prevent some problems, such as the umbilical cord being squeezed. If the umbilical cord is squeezed, the baby doesn’t get enough food and oxygen.

If the fluid gets too low or if your baby is having trouble staying healthy, your provider may recommend starting labor early to help prevent problems during labor and birth. However, with regular prenatal care, chances are that your baby will be born healthy.

What can you do if you have oligohydramnios?
Drinking lots of water may help increase the amount of amniotic fluid. Your provider may recommend less physical activity or going on bed rest.

Is oligohydramnios common?
About 4 out of 100 (4 percent) pregnant women have oligohydramnios. It can happen at any time during pregnancy, but it’s most common in the last trimester (last 3 months). It happens in about 12 out of 100 (12 percent) women whose pregnancies last about 2 weeks past their due dates. This is because the amount of amniotic fluid usually decreases by that time.

Last reviewed June 2011

See also: Polyhydramnios