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Amniotic Fluid: What You Need to Know

The liquid surrounding your baby-to-be is much more than a watery home: It's a cushion that protects the fetus from physical trauma (if you fall, for instance), a shield against infection, and a backup source of fluid and nutrients. It also helps the baby's digestive and respiratory systems develop properly.

During your first 16 weeks, this fluid is produced by the placenta, the fetus's skin, and the umbilical cord. After that, it consists also of recycled urine: The fetus swallows the liquid, which is processed through the kidneys and excreted in a continuous cycle. You have 800 to 1,000 milliliters of fluid by your third trimester (three-and-a-half to just over four cups), says Brian S. Carter, M.D., associate professor of pediatrics at Vanderbilt University Medical Center, in Nashville, TN. Your doctor can check your amniotic fluid by ultrasound if he suspects a problem.

When Levels Are Too High:

Too much amniotic fluid can indicate a birth defect, such as a gastrointestinal blockage, or in some cases a chromosomal problem in the fetus. Signs of excess fluid (which affects 1 percent of pregnant women) include decreased fetal movement and a noticeable increase in the size of the baby’s abdomen. No need to worry though: Most women with this condition go on to deliver healthy babies.

When Levels Are Too Low:

An inadequate amount of fluid, which affects 4 percent of expectant women, can be caused by a tear in the amniotic membrane, problems with the placenta, or an infection, such as an STD. Without enough amniotic fluid to float in, a fetus can sit on the umbilical cord and cut off its blood supply, and if amniotic fluid volume is too low for many weeks, the baby might be born prematurely, and/or with poor lung development and premature delivery.

Signs of low amniotic fluid volume can include leaking fluid, a smaller-than-average belly on the mother, and decreased fetal movement. You're at greater risk if you have chronic high blood pressure.

What You Can Do:

If you suffer from either condition, your doctor will probably administer regular nonstress tests and ultrasounds for the rest of your pregnancy and, in some cases, may even put you on bed rest. Too much fluid may be treated with medication. Drinking an extra eight cups of water a day can help women with too little fluid increase their levels.

Nichole Cipriani is a freelance writer.