Pregnancy is full of amazing changes. Anyone who has experienced it can tell you that this transformative process is a lot of work! And for good reason—building a new person is a big deal! From two single cells, we produce all that is needed to grow and sustain human life for about 40 weeks. Among the incredible creations our bodies produce is a whole new organ: the placenta.
Anatomy
The placenta is a soft, spongy organ that at full-term measures about 9 inches in diameter—that’s about the size of a dinner plate—and weighing about 1-2 lbs. It makes up one portion of the amniotic sac, which surrounds the baby. The placenta is anchored to the uterus, and connects to the baby via the umbilical cord. The umbilical cord is a firm-but-slippery tube, which averages about 55 centimeters (about 21 inches), and contains two arteries and one vein. The umbilical cord connects with the baby’s belly, and after birth, the attachment site becomes the navel.
Function
The placenta serves many important functions in supporting the life of the growing baby. It serves as the bridge between mother and baby, and while it keeps their blood supplies separate, it enables the transportation of nutrients and oxygen to the baby, and the elimination of waste from the baby. As the baby grows, the placenta functions in place of the baby’s developing lungs, liver and kidneys. As the mother eats and breathes, the nutrients and oxygen are absorbed into her blood stream, then passed through the placenta, into the umbilical cord, and finally arriving inside the baby, where is absorbed and nourishes the baby. As the baby produces waste, it is removed via the umbilical vein, and taken to the mother’s bloody supply, where it is eliminated by her kidneys, liver and lungs.
Placement
The placenta can grow anywhere on the uterus, and its placement can have some effect on how a mother experiences her pregnancy. An anterior placenta (located in the front of the belly) can dampen the baby’s kicks and punches and make it harder to feel movement. If the placenta grows at the bottom of the uterus, it can cover the opening (the cervix), preventing the possibility of a vaginal birth. However, as the uterus grows upward, the placenta often moves away from the cervix.
Photo: Norman Barker, Johns Hopkins School of Medicine
Birth
At birth, the placenta continues to function, providing oxygen and nutrients to the baby, and at any given time, holds about one third of the baby’s total blood volume. After the baby is born, the umbilical cord can continue to pass blood and nutrients to the baby for up to about 20 minutes. At that point, the uterus contracts, and the capillaries connecting the placenta to the uterus constrict and the blood flow slows to a stop. The umbilical cord empties the remaining blood into the baby, and becomes limp and white. This is the point when many choose to clamp and cut the cord. The uterus then contracts, disconnecting the placenta, and expels it through the vagina.
After-Birth Rituals
Women over time and across many cultures have practiced different traditions and rituals with the placenta after it has been born. In some cultures it is common to plant the placenta in the garden or under a tree, representing a return of sustenance to earth. Some women pack their placenta with herbs and spices, dry it out, and keep it attached to their baby until it falls off on its own. (This is called a lotus birth.) An increasingly popular practice is to have the placenta dried and ground down into a powder, and put into capsules which are consumed by the mother over the course of the weeks and months following birth. This is thought to support lactation and hormonal stability.
There is no doubt that the placenta is an incredible organ. It enables and sustains the growth of our children, and accomplishes all this without our direction or conscious thought. If you ever get a chance to see one, I challenge you to take it, and to take a moment to appreciate this amazing creation.