De Quervain's is a condition in which the tendons from the thumb to the wrist become inflamed and rub against the "tunnel" that encloses them, causing sensations from mild discomfort to severe pain on the thumb side of the wrist.
Though anyone can develop de Quervain's, it's most common in new mothers and usually stems from stress on the wrist resulting from lifting a baby frequently. A 2009 study from the University of Colorado found that women are four times more likely to develop de Quervain's than men. Michelle G. Carlson, M.D., an orthopedic surgeon specializing in hand and upper extremities at New York's Hospital for Special Surgery, estimates that the ratio is even higher. "I'd say it's about 90 percent new moms," she says.