Water deliveries have no proven benefits for mothers and may lead to serious health problems for babies, U.S. doctors advise.

For mothers, laboring in water may help ease pain, lower the need for anesthesia and potentially speed up the early, or first, stage of labor before the cervix is fully dilated and the baby is ready to emerge, according to new recommendations from the American College of Obstetricians and Gynecologists (ACOG).

But women should get out of the water before the second stage, when it's time to push.

"No specific maternal or infant risks have been identified with first stage immersion," said Dr. Joseph Wax, chairman of ACOG's committee on obstetrics practice and an author of the guidelines.

"Potential infant risks of second stage immersion include fresh water drowning, serious infection, umbilical cord (snapping) with (bleeding) and need for transfusion," Wax added by email.

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Previous studies included in a 2009 Cochrane review suggest that labor in water may be associated with 10 percent lower odds of epidural anesthesia use by women, the ACOG guidelines note.

In addition, labor in water averaged about 32 minutes shorter than outside of water, the review of studies found.

It's not clear from earlier studies whether the water labor itself, or other aspects of the labor and delivery experience such as the more frequent presence of doctors or nurses in the room might have influenced these results.

At the same time, some undesirable outcomes of birth appear similar in and out of the water. Women in both circumstances are equally likely to experience tearing, require a procedure to cut the skin between the vagina and anus to make more room for the baby to pass, or to need forceps or other tools to help the infant out.

Still, some women may want a water birth as an alternative to a medicated or hospital birth experience. Statistics are hard to come by, but one study found about 9 percent of babies in the U.K. had water births last year.

While laboring in the water may not necessarily benefit women, it's reasonable for women to try this as long as they're healthy and haven't had any complications during pregnancy, according to the ACOG recommendations.

Women offered this option should be delivering their babies at full term - from about 37 through 41 weeks gestation - and not earlier or later, the guidelines advise.

When hospitals or birthing centers do allow women to get in the water during labor, they should have a rigorous process for cleaning tubs and pools to minimize infection risk, the recommendations also note.

Even in the water, women and babies still need regular monitoring for signs of distress, and doctors need to be ready to remove women from tubs if urgent problems develop.

In the U.S., most hospitals don't provide water labor and delivery, noted Dr. Amos Grunebaum, chief of labor and delivery at NewYork-Presbyterian Hospital Weill Cornell Medical Center.

The U.S., however, has more planned home births than any other industrialized country, and at least some of these may be water births, Grunebaum, who wasn't involved in the ACOG recommendations, said by email.

Home births are associated with a much higher risk of infant injury and death than hospital deliveries, and it's possible that infections or other complications from water births might explain some of the added risk, Grunebaum added.

"The new recommendations reinforce that immersion in water during the second stage is an experimental procedure that should only be performed as part of a clinical research trial with informed consent," Grunebaum said.