Amniotic fluid

liquid-like substance filling the membranous sac that surrounds a fetus in the womb

Amniotic fluid is the watery liquid surrounding and cushioning a growing fetus within the amnion. It allows the fetus to move freely without the walls of the uterus being too tight against its body. Buoyancy is also provided.The amnion grows and begins to fill, mainly with water, around two weeks after fertilisation. After a further 10 weeks the liquid contains proteins, carbohydrates, lipids and phospholipids, urea and electrolytes, all which aid in the growth of the fetus. In the late stages of gestation much of the amniotic fluid consists of fetal urine.
See more at Wikipedia.org...

Amniotic fluid n. The fluid within the amnion that surrounds the fetus and protects it from injury. [more]Amniotic fluid - Community and Resources

Noun
1. the serous fluid in which the embryo is suspended inside the amnion; "before a woman gives birth her waters break"
(synonym) amnionic fluid, waters
(hypernym) liquid body substance, bodily fluid, body fluid, humor, humour
(part-holonym) amniotic cavity

The fluid bathing the fetus and serving as a shock absorber.