WASHINGTON — Sitting in a tub of warm water can relieve a mom-to-be’s pain during the early stages of labor, but actually giving birth under water has no proven benefit and may be risky, say recommendations for the nation’s obstetricians.

There’s no count of how many babies in the U.S. are delivered in water, but it is increasingly common for hospitals to offer birthing pools or tubs to help pregnant women relax during labor.

In a report released Thursday, a distinction is made between the two uses, saying that early on immersion may be helpful, as long as some basic precautions are taken.

But there has been little scientific study of underwater delivery, along with a handful of reports over the past decade or so of near-drownings and other risks to the infant, said the joint opinion from the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics.

Although complications appear to be rare, the report urges that underwater deliveries be performed only in research studies to settle the questions. “Laboring in water is not the same as delivering under water,” said co-author Dr. Jeffrey Ecker of Harvard University, adding that he’s cared for numerous women who were comforted by immersion during labor.

As for delivery, “We want people to do more research,” said ACOG committee member Dr. Aaron Caughey of Oregon Health & Science University.

The report says potential risks of underwater delivery include infection, difficulty regulating the baby’s body temperature and respiratory distress if the baby inhales water.