Amniotic Fluid

What is amniotic fluid?

Amniotic fluid is a water-like substance that surrounds and protects a fetus during pregnancy. It plays an important role in fetal development because it helps develop a fetus’s muscles, lungs and digestive system. It also acts as a cushion, protecting them from impact (like a shock absorber). Amniotic fluid contains nutrients, hormones, antibodies and other fluids that the fetus swallows and pees out. While it sounds unpleasant, it’s healthy for the fetus to swallow and breathe in amniotic fluid.

Having too little or too much amniotic fluid could cause problems for a pregnant person or the fetus. For this reason, pregnancy care providers have ways to monitor how much amniotic fluid you have. Samples of amniotic fluid can check the fetus for genetic conditions (amniocentesis).

What does amniotic fluid do?

Amniotic fluid is important for fetal growth and development. It helps prepare the fetus for the outside world. Here’s what it does:

• Protects the fetus from infection.
• Cushions the fetus’s movements and helps it move.
• Helps the fetus’s muscles and bones develop so it can move more freely.
• Prevents the umbilical cord from compressing. The umbilical cord transports oxygen and nutrients from you to the fetus and could become squished without amniotic fluid.
• Helps the fetus’s digestive and respiratory systems develop because it breathes in and swallows the fluid.
• Contains antibodies to help strengthen the fetal immune system.
• Regulates fetal body temperature.
• Protects it from your movements (like when you jump or if you fall).

What is amniotic fluid made of?

Amniotic fluid is mostly water (from your body) for the first half of pregnancy. The fetus’s pee makes up most of the amniotic fluid after about 20 weeks of pregnancy. This is because, like adults, the fetus will swallow liquid and pee it out. The rest of the fluid contains hormones, lipids, carbohydrates, antibodies and other nutrients.

Where is amniotic fluid?

Amniotic fluid is inside the amniotic sac. Picture a balloon filled with water. The amniotic fluid is the water, and the balloon is the amniotic sac. When the sac (or balloon) opens, the fluid (or water) leaks or gushes out.

What color is amniotic fluid?

Amniotic fluid is mostly clear but can be a pale yellow like the color of straw. Amniotic fluid that’s tinted brown or green means the fetus has passed meconium (their first poop). Meconium in amniotic fluid can cause complications if the fetus breathes it in.

What does amniotic fluid smell like?

Amniotic fluid should be odorless. Contact your healthcare provider if you notice a foul smell as it could be meconium-stained or mean there’s an infection.

It’s common for pregnant people to leak pee, so some people have difficulty distinguishing amniotic fluid from pee. Inspecting your underwear for smells or color can help you determine what it is. Pee has a unique smell and may be easier to control than amniotic fluid.

How much amniotic fluid is normal?

It depends on how far you are in your pregnancy. Your amniotic fluid levels peak at 34 to 36 weeks and then slowly decrease as you reach your due date (40 weeks). At its peak, there’s a little less than 1 liter (about 4 cups or 1 quart) of amniotic fluid.

What are possible health conditions affecting amniotic fluid?

Your pregnancy care provider checks for signs that your amniotic fluid is healthy and that you have enough of it. Some of the conditions that affect amniotic fluid are:

• Oligohydramnios (low amniotic fluid): Low amniotic fluid in the first six months of pregnancy is generally more dangerous. These complications could include miscarriage, physical deformities of the developing fetus or premature birth. Later in pregnancy, low amniotic fluid can cause umbilical cord compression or intrauterine growth restriction.
• Polyhydramnios (too much amniotic fluid): Having too much amniotic fluid causes symptoms like swollen feet, breathlessness or constipation. It can put pressure on neighboring organs, too. Complications include premature birth, macrosomia or stillbirth.
• Chorioamnionitis: When bacteria cause an infection of the amniotic fluid. Your pregnancy care provider treats the infection with antibiotics. Without treatment, it can lead to serious pregnancy complications.
• Premature (prelabor) rupture of membranes: This is when you leak amniotic fluid before 37 weeks of pregnancy and before labor starts. Allowing a pregnancy to continue after your water breaks can increase your risk of infection and complications.

How is amniotic fluid measured?

Your pregnancy care provider can measure the amount of amniotic fluid you have in a few different ways. The easiest way to measure it is through a prenatal ultrasound. But since you won’t receive ultrasounds every visit, your provider will use a measurement called fundal height to estimate if you have enough amniotic fluid.

Can drinking water increase amniotic fluid?

No one is entirely sure if drinking more water can increase amniotic fluid. Some healthcare providers will recommend a pregnant person increase their water intake if their fluid is low. There’s no harm in drinking more water during pregnancy but talk to your provider first to see what they recommend.

What happens if a fetus runs out of amniotic fluid?

A fetus needs some amniotic fluid in the uterus to survive. The exact amount of amniotic fluid it needs depends on how many weeks pregnant you are and other factors.