A thin fluid filled membrane that surrounds and protects the developing embryo

Amniotic fluid is the fluid that surrounds your baby during pregnancy. It’s very important for your baby’s development.

How does amniotic fluid keep your baby healthy?

During pregnancy, your baby grows inside the amniotic sac (bag) inside your uterus (womb). The sac is filled with amniotic fluid. This sac forms about 12 days after getting pregnant. Here’s what the fluid does:

• Cushions and protects your baby
• Keeps a steady temperature around your baby
• Helps your baby’s lungs grow and develop because your baby breathes in the fluid
• Helps your baby’s digestive system develop because your baby swallows the fluid
• Helps your baby’s muscles and bones develop because your baby can move around in the fluid
• Keeps the umbilical cord (the cord that carries food and oxygen from the placenta to your baby) from being squeezed

In the early weeks of pregnancy, the amniotic fluid is mostly water that comes from your body. After about 20 weeks of pregnancy, your baby’s urine makes up most of the fluid. Amniotic fluid also contains nutrients, hormones (chemicals made by the body) and antibodies (cells in the body that fight off infection). 

How much amniotic fluid should there be?

The amount of amniotic fluid increases until about 36 weeks of pregnancy. At that time, it makes up about 1 quart. After that, the amount of amniotic fluid usually begins to decrease.

Sometimes you can have too little or too much amniotic fluid. Too little fluid is called oligohydramnios. Too much fluid is called polyhydramnios. Either one can cause problems for a pregnant woman and her baby. Even with these conditions, though, most babies are born healthy. 

Does the color of amniotic fluid mean anything?
Normal amniotic fluid is clear or tinted yellow. Fluid that looks green or brown usually means that the baby has passed the first bowel movement (meconium) while in the womb. (Usually, the baby has the first bowel movement after birth.)

If the baby passes meconium in the womb, it can get into the lungs through the amniotic fluid. This can cause serious breathing problems, called meconium aspiration syndrome, especially if the fluid is thick.

Some babies with meconium in the amniotic fluid may need treatment right away after birth to prevent breathing problems. Other babies are healthy at birth may not need treatment, even if the amniotic fluid has meconium.

There are probably several things you need to get done on a daily basis. You might have to head to your office, take a bus ride, go grocery shopping, or set up your nursery. While you might be used to a busy schedule, you’ve got another thing to worry about while rushing around: your baby.

Every step, bend, waddle, and shimmy you take can feel like a perceived hazard. And while you’ll want to avoid heavy lifting and extreme sports, you’ve got something on your side — something that’s there all the time to protect your little one from life’s demands. Meet the amniotic sac!

What is the amniotic sac, exactly?

The amniotic sac is filled with the famous “water.” You know, the thing that breaks in movies (and sometimes in real life) before labor begins (though the membranes most often rupture right at the beginning or during labor). In any case, the amniotic sac does a lot more than tell you when your baby is about to arrive.

This fluid-filled bag protects the fetus from the outside world, helping to regulate its temperature and safeguarding it from injury. The amniotic sac is filled with amniotic fluid and has two thin layers (or membranes). The inner layer surrounds your growing baby, and the outer membrane wraps around once more, providing an extra layer of protection. In short, your little one lives in a tough, protective bubble inside your womb.

What to know about amniotic fluid

Just days after conception, the amniotic sac starts to form. Maybe even before you know it, your baby’s new home will take shape and begin filling up with a clear or potentially yellowish liquid (AKA amniotic fluid). This protective substance is pretty impressive, providing a number of essential functions through all three trimesters.

Umbilical cord support: The all-star umbilical cord is responsible for delivering oxygen-rich blood and nutrients to your baby. But the unsung hero of the story is amniotic fluid. Though it takes on a supporting role, the liquid ensures the umbilical cord can do its job by preventing it from getting squeezed or compressed when your baby moves around.

Temperature control: Have you ever stayed in the bath so long the water got cold? It’s not the most pleasant experience. Fortunately, your baby won’t have to deal with this issue, thanks to amniotic fluid. The liquid prevents heat loss, ensuring your little one stays nice and warm while inside the womb.

Room to move: Amniotic fluid also helps your baby develop muscles and bones by providing room to move around. This might help you see all those kicks in a new light.

Infection protection: Amniotic fluid contains essential nutrients and antibodies, which can help both you and your baby fight off infections.

Lung development: Last but not least, the amniotic sac helps your baby practice breathing and swallowing. They actually breathe in the fluid, which helps their lungs develop and grow strong.

The takeaway

When you’re going about daily life, it’s good to be aware of your surroundings to avoid bumps and falls. That said, you might have a little more peace of mind knowing the amniotic sac is always in your corner.

What is a thin fluid filled membrane?

What is the membrane that develops around the embryo?

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