Once there is an anchor baby, my understanding is then mother and baby become eligible for many welfare benefits. Like Medicaid, Food Stamps, Section 8, etc.
Gerry, this assumes that welfare benefits are so attractive that illegals come here to draw them. In most instants, it is illegal for them to draw benefits. Most of them have a network that makes it easy to find work. Family ties are usually very strong, so as a result, most come here because a brother or cousin has located work for them.