Researchers at Northwestern University found that the common practice of eating the placenta after childbirth does not have health benefits— and may have unknown risks.

The placenta is an organ that keeps the unborn baby’s blood supply separate from its mother’s, and is linked to the baby by the umbilical cord. Oxygen and nutrients flow from the mother’s blood supply to the unborn baby’s and waste products from the baby pass through the placenta into the mother’s blood stream.

Common claims of the trend, where mothers eat the placenta— either raw, cooked, or encapsulated, say that the practice offers protection against postpartum depression, reduces post-delivery pain, boosts energy, aids lactation, promotes skin elasticity, enhances maternal bonding, or replenishes iron in the body.

In the study, published in Archives of Women’s Mental Health, researchers reviewed 10 current published research studies on placentophagy.

The risk of eating placenta is unknown, for both the mother and child.

"Our sense is that women choosing placentophagy, who may otherwise be very careful about what they are putting into their bodies during pregnancy and nursing, are willing to ingest something without evidence of its benefits and, more importantly, of its potential risks to themselves and their nursing infants," lead author Cynthia Coyle, a Northwestern University Feinberg School of Medicine faculty member and a psychologist, said in a press release.

Placenta storage and preparation are not regulated, and dosage is inconsistent, researchers added.

Study authors note that more research is needed to understand what exactly is in the placenta.

In recent years, the practice has increased in popularity, with celebrities such as Kourtney Kardashian talking about the benefits.

“Our sense is that people aren’t making this decision based on science or talking with physicians. Some women are making this based on media reports, blogs and websites,” corresponding study author Dr. Crystal Clark, an assistant professor of psychiatry and behavioral sciences at Northwestern, said in the news release.