10 incredible facts about the placenta
The placenta is mysterious but mighty. The only transient organ in the body (meaning it grows, then leaves), belonging to both the mother and the fetus, the placenta is a major part of our little corner of class Mammalia. The organ grows in the uterus and hooks into the mother’s body to provide the fetus with oxygen, blood, and nutrients. Although scientists have plenty of questions about it—there’s no way of studying it as it develops—what we do know proves how amazing the placenta is.
1. THE PLACENTA FUNCTIONS AS NUMEROUS ORGANS IN ONE.
Shaped like an umbrella over the baby, the placenta functions as multiple organs in one. It acts as the baby’s lungs by providing oxygen from the mother, as its kidneys by filtering out waste product, and as its gastrointestinal and immune system by delivering nutrients and antibodies. It keeps the mother’s blood supply separate from that of the fetus, while also helping pass nutrients from the former to the latter. The placenta is what allows the fetus grow to a healthy size before birth.
2. MAMMALS AREN'T THE ONLY ANIMALS THAT MAKE PLACENTAS.
Although some amphibians give live birth [PDF], it’s incredibly rare for them to develop true placentas. That’s one thing that makes skinks so unique. A few species of these lizards have almost no yolk in their eggs, so the embryo needs to get nutrition from the mother. But oddly, despite appearing in a few different species of skink, the placentas are evolutionarily unrelated to each other, indicating that it might have evolved three separate times.
3. THE PLACENTA COMMUNICATES WITH THE MOTHER USING BITS OF ITSELF CALLED EXOSOMES.
One of the biggest difficulties for doctors is that the placenta can’t be monitored for growth or invasiveness through the mother’s pregnancy. If the blood vessels don’t develop correctly, they limit the blood flow to the placenta, which can result in preeclampsia, or the placenta could be penetrating too deeply into the mother’s uterine wall (or, more rarely, organs), a condition called placenta accreta. But researchers recently discovered that exosomes (tiny vesicles secreted by the body’s organs) released by the placenta might offer a noninvasive way of monitoring the placenta’s growth. The study found that at delivery, the concentration of placental exosomes correlated with the weight of the placenta. There’s more work to be done before a reliable blood test can be developed to monitor the mother’s placenta, but it could someday help doctors save women who develop dangerous conditions like preeclampsia.
4. WOMEN WHO LIVE AT HIGH ALTITUDES MAKE MORE EFFICIENT PLACENTAS.
“The evolutionary pressure on placentas is huge. It’s an evolutionary pressure much more serious than a minor tweaking of your bone structure,” says Stacy Zamudio, senior scientist and director of research at Hackensack University Medical Center. To show just how sensitive the placenta is to environmental forces, Zamudio studied indigenous women living at high altitudes in the Andes. She found that their placentas resulted in larger babies than women who had more recently moved to high altitude communities. The women whose communities had lived at high altitude for generations were more efficient at drawing oxygen from the thin air, which in turn changed the development of their placentas.
5. THE PLACENTA GIVES THE MOTHER'S IMMUNITY TO THE FETUS.
6. OBESITY HAS NUMEROUS NEGATIVE EFFECTS ON THE PLACENTA.
7. EATING THE PLACENTA HAS NO KNOWN HEALTH BENEFITS—BUT PEOPLE DO IT ANYWAY.
You may have heard about the sudden popularity of mothers eating their placentas after giving birth (celebrity practitioners include everyone from Kim Kardashian to January Jones). It’s a practice known as placentophagia, and plenty of other mammals do it, though that doesn’t mean it’s helpful to Homo sapiens. The women who choose to consume their placenta—raw, cooked, or in powdered capsules—claim it works as a preventative against postpartum depression or promotion of lactation, but a review of current studies found no evidence for any of the claims.
8. DIFFERENCES IN THE PLACENTA ACROSS MAMMALS MIGHT BE RELATED TO RISK OF INFECTIONS.
9. EACH TIME A WOMAN GETS PREGNANT, A NEW PLACENTA GROWS.
10. SCIENTISTS STUDY THE PLACENTA TO UNDERSTAND CANCER.