Requiring health care professionals to report underage sexual activity?

The NYT reports:

A federal trial opened here Monday over whether a Kansas law prohibiting virtually all sexual activity by people under age 16 means health care professionals and educators must report such behavior to state authorities, which some say would stop many teenagers from seeking contraception or treatment for sexually transmitted diseases.

The class-action lawsuit stems from a 2003 opinion by the Kansas attorney general, Phill Kline, a conservative Republican who has developed a national reputation for fighting abortion....

Mr. Kline's interpretation of the law focused mainly on the reporting duty of abortion providers, arguing that any pregnant, unmarried minor had by definition been the victim of rape or abuse. But it included a broad mandate for reporting whenever "compelling evidence of sexual interaction is present."...

"If they know what they tell me is reported, they simply won't talk," said Beth McGilley, a Wichita therapist who is among the plaintiffs, referring to both teenage clients and adults who often consult her about their children's sexual exploration.

It's a harsh policy, but is it unconstitutional?

Bonnie Scott Jones, a lawyer for the Center for Reproductive Rights in New York, which is representing the plaintiffs, said in her opening statement that Mr. Kline's "dragnet approach" to amassing information on under-age sex violated minors' privacy rights and the Constitution's equal protection clause, and that it "seriously endangers the health and well-being of adolescents."...

Steve Alexander, an assistant attorney general defending the suit, said the Kansas statute meant that those younger than 16 could not consent to sex, and that those violating the law forfeited any privacy rights.

"Illegal sexual activity by minors can lead to S.T.D.'s, unwanted pregnancies, abortion, depression, mental illness," Mr. Alexander said. "To pretend otherwise is foolish."

Surely, you don't want to pretend anything foolish.

Actually, I'd like to see more of what the legal arguments are here. It looks as though the case is mostly about interpreting a state statute, but there is also a constitutional attack. Presumably, the constitutional attack is both part of the argument for narrowly construing the statute and a device to get the case into federal court. Shouldn't the federal court abstain and let the state court interpret the state statute?