I had a cousin who did that. She ended up with I think five girls, I don't know if they ever got a boy. I always thought it would've been funny if they had girl triplets or something, but in retrospect it would've been horrible.
Stephanie doesn't seem like the type of woman to allow herself to be turned into a human conveyor belt.
Anyway, there are certain processes couples can undergo to ensure they have either a girl/boy. But that's only usually used in cases of genetic disorders that are more likely in in a certain sex, I think. I don't think normal people can have it if they have no good reason to.
Knowing my cousin, they'd let them do that just to minimize their reproduction.