You’d think, being land-based mammals, we’d all be able to agree on the basic fact that humans breathe air, and that newborn human babies ought to be born into the air.  You know, so they can breathe. That’s how human babies have always been born, and that’s how all other primates are born, and that’s how all other land mammals are born. (Hats off to our cetacean cousins for their sticking to their evolutionary guns on the water birth. Unlike humans, Flipper doesn’t do well in air.)

And yet, there’s always someone willing to wonder, “Could there be a better way?” Immersion in water during labor or birth is touted by some as beneficial to both mother and baby. What does the evidence show? I’m willing to suspend common sense, here—show me it’s safe, then, sure, let’s join the dolphins.

Except it isn’t safe. And the purported benefits? No so much.

In a joint statement from the American Academy of Pediatrics and the American Congress of Obstetricians and Gynecologists, physicians have reviewed what we know and don’t know about water birth. What we do know, really, is very little — studies are of limited quality and small scope, and use varying methods and varying definitions of “water birth.”

Many of the “studies” are not in scientifically reviewed journals, and are more like collections of cherry-picked stories than actual objective evidence. Most of these “studies” show zero objective benefit during labor, though some pooled studies combining case series show a reduced use of anesthesia and a reduced time of labor during immersion in water. However, no matter how the data are combined, there’s no difference in perineal trauma, tears, c-section rates, or a need for assisted delivery. And there are no individual trials or pooled collections that show any benefit to the newborn infant at all.

What there are, though, are several case reports and case series of babies suffering harm from water birth. Because the numbers of women undergoing labor or birth in a water bath aren’t known, we can’t estimate the rates of these complications. But the complications are real and can be devastating: umbilical cord tears leading to hemorrhage and shock,  hypothermia, drowning, seizures, brain damage, and death. Are these kinds of risks an acceptable trade-off for the meager, unproven benefits of water birth?

The ACOG and AAP point out that immersion in water during what’s called the first stage of labor — the early part, when there are regular contractions but the cervix isn’t fully dilated — may be appealing to some women, and may offer some potential benefit in terms of pain control. Even though there’s no evidence of benefit to the baby, as long as immersion doesn’t otherwise interfere with good care it’s not unreasonable. Rigorous protocols ought to be in place, though, to protect mom and baby — including maintenance and cleaning of the tubs, infection control and monitoring, and careful observation for signs that it’s time to move out of the tub. Before someone gets hurt.

However, immersion during the second stage of labor, when the cervix is dilated and Junior is making his way into the world we share — that’s of zero benefit, and can lead to great harm. Humans are not water creatures, and it’s not likely that our babies really ought to be born underwater.

Roy Benaroch is a pediatrician who blogs at The Pediatric Insider. He is also the author of Solving Health and Behavioral Problems from Birth through Preschool: A Parent’s Guide and A Guide to Getting the Best Health Care for Your Child.