Floralba Fernandez Espinal rose at 6:50 that morning. For the first time in weeks she felt no misgivings about going to work, no anxieties about her pregnancy.

The letter from her obstetrician was going to make everything all right.

For two years, Ms. Fernandez has worked at Unique Thrift, a national chain of thrift shops with a store in the Kingsbridge section of the Bronx. Day in and day out, she has carried heavy piles of clothing — coats, jeans, dresses, blouses — from the storeroom to the showroom, where they are hung on racks.

But Ms. Fernandez is three months pregnant now. She had a miscarriage last year and feared that her unborn child might be at risk. She had seen other workers transferred temporarily to different positions — working the cash register or tagging and hanging clothing — and asked if she could do the same.

Bring in a doctor’s note, her boss said.

So on Jan. 9, Ms. Fernandez packed the note in her lunch bag. She handed it in before she took off her coat, before she clocked in, before she pulled on the burgundy apron she wears on the job. The letter from her doctor at NewYork-Presbyterian Hospital was clear: “No lifting, pushing or carrying heavy objects or loads.”