Michael Katz, chief of obstetrics at California Pacific Medical Center in San Francisco, said bed rest is "not healthy, it's not helpful and it's potentially detrimental."
"It's something I'm staying away from more and more," Katz told The Wall Street Journal.
Remaining in bed for extended periods has long been prescribed for women who are at risk for preterm delivery labor or have high blood pressure, bleeding or other complications.
However, studies failed to turn up evidence bed rest improves these conditions, and some research has shown being confined to bed could cause health risks of its own, including blood clots and a temporary loss of bone-mineral content, the Journal reported.
Yet, as many as 20 percent of U.S. women are placed on bed rest in the latter half of pregnancy, some estimates show. Experts say some physicians fear liability if a complication arises and the doctor didn't take action. In addition, some mothers want to feel they are minimizing risks to their unborn babies, the Journal said.