Amniotic fluid is the fluid found in the amniotic sac that surrounds a developing fetus in the uterus. In addition to cushioning and protecting the developing fetus, it also plays a role in the transfer of nutrients between the mother and the fetus. It is created from the mother's plasma.
Early on in pregnancy, the fluid is mostly water and electrolytes, but as the fetus develops, the fluid also starts to contain protein, carbohydrates and fat. The amount of fluid also increased during pregnancy.
The fluid can be collected for diagnostic purposes, but routine collection is not recommended due to the risk to the fetus.