Ergo!

Fiorella told the psychologist that she remembered when her mother, Fio's new baby brother in her arms, was carried into the house on a gurney.  The whole neighborhood was gathered around in the front room. and when the ambulance personnel halted the gurney, Fio looked at the baby and said, "He's wide asleep."
Everyone laughed, but in a warm way, which made Fiorella feel good.

The psychologist told Fio this was a false memory, that post-partum women were not brought home on gurneys, even back them.

Fiorella stubbornly held onto the memory, which was just as real as when she and Janet Orcutt (Janny Orchid) washed their dolls in the Orcutt bathroom sink and saw their painted faces slide off.  Or when she sampled some of the cherries from the Orcutt cherry tree and discovered they were sour.  Or when she realized she'd gotten a strawberry stain on the front of her new sailor dress.

Which is all building up to Fiorella waking up this morning with PROOF, albeit circumstantial, that her mother came home on a gurney: she remembered that, years later, Mother told her that the woman who who took care of Baby during her convalescence was careful that Fio never saw him naked.

Which means that Mother was not immediately able to care for Baby when she came home from the hospital--ON A GURNEY.