"Mommy Thumb" (De Quervain's tendinitis)

...mommy thumb, formally known as De Quervain's tendinitis, an inflammation of the tendons below the thumb down to the wrist. Although the condition has been around as long as parents have hoisted their children, doctors say a combination of heavier children, older new mothers, cribs that are lower to the floor and frequent scrolling and typing on smartphones has sent the number of cases skyward.

Orthopedic surgeons estimate that between one-quarter and one-half of new mothers experience symptoms of De Quervain's. When common pain relievers don't ease the inflammation, patients are getting steroid injections, splints and even surgery...

People with De Quervain's typically experience pain on the thumb side of the wrist that radiates up the forearm. Sometimes the symptoms start during pregnancy. Doctors aren't sure why, but they believe that swelling adds pressure to already stressed tendons, exacerbating the irritation. For many women (and some men), it gets worse when they are constantly lifting a child, bending down into the crib, putting their hands in an "L" shape under the child's armpits and lifting so that much of the weight is on the thumbs.

The rest of the story is at The Wall Street Journal.

p.s. - I wonder why "tendon" is spelled with an "o" but "tendinitis" and other derivatives are spelled with an "i".