If she gets a visa, green card or some other immigration papers from INS. Having a baby in the US does not instantly grant immigration papers.
I agree with the last poster. Sometimes US immigration laws are rough.
And: No. She will not be admitted iun the USA, just because she had a child here. She has to get a visa some other way. Her child can only apply for a green card for her mother when the child reaches the age of 21 years old.