> You can get into the US on a car, train, boat, bicycle or a good pair of chanclas.

What does it buy you to trade one expensive ticket for another? I don't think you're seriously suggesting that walking here from even Central America is not a large impediment, to say nothing of the unconnected continents where the large majority of people actually live.

> You certainly don't need to be here nine months to have a kid.

The alternative is to get a travel visa when you're already pregnant, in which case the government can observe what you're attempting to do and deny the visa.

> You can certainly find work in that time

Working on a travel visa is illegal, therefore harder to do and lower paying.

> and emergency medical care is "free"

That implies going through a pregnancy with no access to non-emergency medical care (e.g. ultrasound), risking the life of the child.

> And while yes, it means more people, those people are a far cry from new immigrants and their numbers can still be limited federally.

Either you're increasing the number of unskilled immigrants or you aren't.