There's a lot going on with this card, sent June 10th, 1910 from Ferndale, California to Eureka, California.
Here's the message:
Get or order sis a maternity corset. Do this at once. Have a case for you soon. Baby O'Leary, over by Enos's. Want it? Attend to this for sis at once, will you? Alice
The nurse is Miss Anderson of the French. Will be here later.
I had never heard of maternity corsets, but it seems that if you were accustomed to wearing a corset from adolescence on, you wouldn't stop when you got pregnant. It may have offered support for the abdominal muscles, but it was also intended to minimize the protrusion of the belly.
The picture on the card is also interesting. It's a colorized photograph by Frank Rinehart from 1905. Although the card doesn't say so, this is most certainly a picture of the actress, Wah-Ta-Waso, a very interesting and accomplished woman from the Penobscot tribe (although she is more often described as being Iroquois.) Born in 1887, she played Chopin on the piano and attended Harvard University. She died in 1974 and is buried in Calvary Cemetery in Los Angeles.