More than Bubble Wrap Of all human bodily fluids, amniotic fluid is the least well studied. Secreted by cells lining the amniotic sac, its most conspicuous function is to serve as a kind of liquid bubble wrap, protecting the fetus from physical trauma. But it also contains elements, such as immunoglobulins, that help ward off infectious injury. New research suggests that amniotic fluid may also help shape the infant's own developing immune system. During the first 20 weeks of pregnancy, the skin of the fetus is whispery thin and lacks the outer waterproofed coating that keeps the rest of us dry in the rain.
Amniotic fluid passes freely through fetal skin and into the body.
This fluid is also inhaled and swallowed as the unborn baby rehearses the motions of breathing and eating. And, of course, this fluid is peed right back out again. As the amniotic fluid bathes the inside and outside of the baby's growing body, it exposes the fetal respiratory and gastrointestinal tract to various immunological factors. According to one new study from the University of Texas in Galveston, this contact may prepare these sites for future work in mucosal immunity. The verdict is still out on exactly how the immunological transformation of amniotic fluid-exposed cells takes place and for what purpose.