That was my thought at first as well, but thinking about it more, if abusers find out that genetic testing is routinely happening they will just not allow the victim to receive medical treatment at all, which would be worse for the victim than the status quo. Worst case scenario they would get rid of the evidence completely, either by forced back-alley abortion or murder.

This seems like a second order effect that is surely much lower than fixing the first order effect of protecting underage pregnant women and arresting their abusers. Surely some abusers would prevent women from getting help, but we shouldn't deny help to those that we can, that just seems utterly crazy to me.

"First, do no harm".

Because a doctor's duty is to their patient, not the justice system. Breaking up the family might not be the best thing for the pregnant girl or newborn. I'm not saying they actively cover up abuse, but doctors know not to ask questions they don't want answered. Blanket genetic testing determinative to determine parentage is very dangerous knowledge.

I'm dubious that this lacks societal benefit overall. Even if we buy that breaking up the sexually abusive family is't the best thing (already dubious), there's strong second order effects of this disincentiving abuse.

Automatic genetic testing also has other advantages of preventing future paternity disputes.

Honestly, this would be an interesting thing for a single state to run an experiment with and see how behaviors change.

While society would no doubt benefit from outing abusers, teen births as a whole are a tiny portion of births. 10% of a small number is a small number.

Given women cheat at the same rates as men, blanket genetic testing would break up a significant amount of families. That's why some countries (France for example) ban paternity tests.

Aren't doctors mandatory reporters in the United States?

Mandatory reporters, not mandatory investigators. If they have no knowledge of the abuse they have nothing to report. If the girl says that her boyfriend is the father, the doctor isn't going to run extra tests just to prove her wrong. There is no medical advantage to the patient in such testing. Doctors are not cops.

Their primary directive legal or not is to uphold the oath they took to do no harm. If reporting would cause them to violate this ancient creed then it is for they to decide what they will do.

Sure, if they want to risk being stripped of their license, they can flout the law.

That law (in this case) is so difficult to enforce that it matters very little.

Their patients would include the mother, wouldn't it?

Ending abuse for the pregnant girl is certainly their prorogative

Locking up child abusers isn't controversial. Finding out the vast majority of them get away with it scot free seems like it would be controversial as hell.

The only controversial thing I can think of here is when it comes to the definition of abuse. People are on the sex offender registry for public urination, although I suspect that this happens more often with repeat offenders.