It’s OK for a woman in labor to take some of the pressure off in a tub, but there’s no advantage to actually giving birth in water and it could be dangerous for the baby, two big doctor groups advised Thursday.

Laboring in a tub may feel good for mom, but new guidelines don’t recommend water births.

The new joint guidelines from the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG) are the first to offer any real professional guidance on a practice that’s had on and off popularity for decades.

“Before this report, there wasn’t any standard advice,” says Dr. Tonse Raju, chief of the pregnancy and perinatology branch the National Institute of Child Health and Human Development, who helped write the guidelines.

“The practice has been going on without a whole lot of endorsement from any major group.”

Water births, where moms labor and sometimes deliver in water, are currently becoming more popular again. Supermodel Gisele Bundchen became a super-advocate when she delivered her son, Benjamin, in 2010 in the bathtub in the home she shares with husband, celebrity NFL quarterback Tom Brady.

However, doctors have shied away from recommending water births.

The report finds that it is safe for mothers with uncomplicated pregnancies to spend the first stage of birth, when they are laboring, in a tub. Laboring in water often reduces a mother’s pains and can relax her.

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