No vital organ may be as underrated as the placenta. Often discarded as an afterthought of afterbirth, the placenta, which links mother and child during pregnancy, serves important health functions. In “Life’s Vital Link,” Y.W. Loke takes a closer look at this little-understood organ, how and why it evolved, and the role it plays in birth.
Compared with such organs as the heart and lungs, the placenta has a very short life span. According to the book, it is created within the fertilized egg and survives only for the duration of a pregnancy, about 270 days.
The book explains that the placenta marked a pivotal shift in evolutionary history, allowing humans and other mammals to birth live offspring instead of laying eggs that develop on their own.
For a fetus, the placenta is a protector and gatekeeper, the book says, providing oxygen and nutrients while its lungs, kidneys and digestive system form.
As far as the mother is concerned, the placenta acts as a parasite, the book says. With DNA from both mother and father, it is a foreign body for the pregnant woman, one that diverts blood and nutrients from mother to fetus and avoids attack by the mother’s immune system. It therefore should be rejected by the mother’s body — but it isn’t.
“This ‘immunological paradox of pregnancy’ has preoccupied immunologists for well over half a century and still the solution remains tantalizingly beyond reach,” Loke writes. “This normally peaceful co-existence between placenta and mother throughout pregnancy is one of the most extraordinary phenomena in reproductive biology.”
This symbiosis allows the baby to receive vital nutrients and helps the mother regulate hormones and spur milk production, the book says.
Because the placenta penetrates deeply into the mother’s uterine lining, it may provide clues to help transplant patients avoid organ rejection, according to Loke. Yet its invasive, aggressive reach makes it very much like cancer. As a result, it can also be of study for oncologists, the book says.