What happens to a wet nurse's own child?

Although no longer common in the West, I want to know what happened to the children of a wet nurse. I mean, to be a wet nurse you clearly had to be lactating, which would usually mean you'd recently had a baby. Unless you had one years ago but became a wet nurse as soon as your own kid was weaned, thus never stopping lactation... or unless you had a stillbirth or infant mortality (which would be sad - "Hey, my baby just died. Lemme just go make the best of it and feed someone else's kid.") Or unless you were simultaneously nursing your own kid and your employer's. Or you pawned off your kid on a cheaper wet nurse, LOL... or maybe you killed your kid to get a job? Gruesome! How did wet-nursing work? Wikipedia is unclear.