At least four things, according to David Atkin's evidence from Mexican maquiladoras:
Workers earn better wages than in non-export oriented industries;
Women who get jobs have taller children;
But youth drop out of school earlier to take the jobs; and
For those that drop out, their wages in the long term are lower than if they had stayed in school and gone to work for the factories later.
The papers, exemplars of careful empirical research, are here and here.