Speaking from a medical point of view regarding screening for abnormal pregnancies and stuff, it is a VERY controversial issue and so many ethical/economical/social factors come into play that I can't even begin to talk about.

As for screening before allowing someone to get pregnant, it's a bit of a far-fetched idea. I mean, people will get pregnant anyways whether they're approved or not, what happens next? Force them to abort? That's another controversial issue. Take the baby away from them?
How can u make sure that those who aren't 'licensed' don't get pregnant?

I'm not always right, but I'm never wrong -Garfield