Amniotic fluid: It’s at once mundane and poetic, a humble liquid that protects and nourishes your baby. It also helps maintain a constant temperature; promotes growth and development of the fetus’s lungs, gastrointestinal system, muscles and bones; and prevents compression of the umbilical cord. Some studies even suggest that it transmits odors and flavors from your diet, helping to influence your baby’s future taste preferences.
After 16 weeks, when the fetus begins swallowing the fluid, it consists partly of recycled urine. The volume increases from about a cup in the first trimester to four cups by the third trimester, then decreases to about three cups at term, says Jeanne A. Conry, M.D., Ph.D., an OB-GYN at Kaiser Permanente in Roseville, Calif.
“Amniotic fluid [levels] can be a reflection of the health of the pregnancy,” Conry says. Clues that there is either too much or too little include decreased fetal movement and a too-large or too-small belly; actual levels can be determined via ultrasound.
Too Little Fluid
This occurs in about 4 percent of pregnancies and can signal birth defects, especially those involving the kidney or urinary tract; premature rupture of your membranes (leaking fluid should be reported to your doctor immediately); or maternal health conditions such as diabetes and high blood pressure. “Too little fluid very early in the pregnancy can impact the actual growth of the infant,” says Conry. “Later, the lack of buoyancy around the umbilical cord combined with contractions can make the baby’s heart rate drop.”
Too Much Fluid
This occurs in about 1 percent of pregnancies and can suggest birth defects, most commonly those of the gastrointestinal and nervous systems that affect swallowing; fetal infection or heart rate abnormalities; or maternal diabetes. Both of these conditions are closely monitored and treatable, and tests are often done to make sure the baby is OK.