Raw, cooked, dehydrated, or steamed placentas: More American mothers are eating the organ that supports their babies after childbirth.

And why, you may ask?

Proponents — who include a small number of celebrities and mommy bloggers — claim it does wonders for new moms, from relieving pain to preventing postpartum depression and enhancing milk production and nutrition.

There’s just one problem: There’s no good evidence that placentophagy — eating one’s own placenta — actually carries any of these health benefits. And a new report suggests moms who engage in the practice may actually harm their newborn babies.

A group of doctors and public health officials from Oregon, writing in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report last week, describe the case of a baby who was born healthy and at term, but then came down with a deadly bacterial infection. The baby was eventually diagnosed with late-onset group B strep disease (or GBS), which caused breathing difficulties. (Complications of GBS can include deafness and developmental disabilities. Up to 6 percent of babies with the disease die.)

After investigating the source of the illness, the doctors found out that the mom had eaten her own placenta after birth in capsule form. They discovered that the strain of bacteria in the placenta pills was the same one that sickened the baby.

The mom, the doctors reported, had requested her placenta after her delivery, and sent it to a company that dehydrated the organ and put it into capsule form. Three days after her baby was born, the mom started eating two capsules filled with her placenta, three times a day. “Consumption of contaminated placenta capsules might have elevated maternal GBS intestinal and skin colonization, facilitating transfer to the infant,” the report said.

The companies that prepare placentas for moms aren’t regulated by the Food and Drug Administration. “No standards exist for processing placenta for consumption,” the authors wrote. Since human tissue can carry infectious diseases and bacteria, if the tissue isn’t properly sterilized, those health risks can be passed on to infants.

In this case, the company (which was not named in the report) claimed it “cleaned, sliced, and dehydrated [the placenta] at 115°F–160°F, then ground and placed [it] into about 115–200 gelatin capsules, and stored at room temperature,” the CDC report said. That clearly wasn’t enough to kill off the harmful bacteria.

Ultimately, the Oregon baby survived the infection after receiving two courses of antibiotics. But the case study demonstrates placenta pills can carry serious health risks, and that new moms should avoid them, the CDC report said.

“Cleaned, sliced, and dehydrated” placenta has no proven health benefits

An online survey of the prevalence of placenta eating after birth found it’s mostly white women who partake in placentophagy — and the practice has been growing in popularity in recent years. Women report hearing about placenta eating in the media, from the likes of celebrity moms Kim and Kourtney Kardashian, January Jones, and Alicia Silverstone who have been touting the benefits of ingesting placenta over the past couple of years.

People who boost placenta eating often note that most mammals (with the exception of camels and aquatic mammals) eat their placentas after birth, and say that this “natural” practice must be good for humans too. They also report doing it to avert or treat postpartum depression.

But as one literature review on placenta eating concluded, the animal data isn’t robust enough to translate to humans, and the human data is also lacking.

Until further notice, new moms should avoid the pills, said Dr. Catherine Spong, a placenta expert and the deputy director of the National Institute of Child Health and Human Development at the National Institutes of Health.

“We have very little information available, and the studies we have do not show any benefit and do not substantiate the claims that are made,” said Spong.

As is often the case, there’s a huge disconnect between celebrity health advice and science — and in this instance, one that carries potentially deadly side effects for babies.