Dood, you're the only one that mentioned abortion. The scenario painted is simply that sex the day before an 18th birthday rose to the notice of someone only, because a girl asked for a pregnancy test -- several months later.
If it makes you more comfortable, maybe it rose to the notice of someone because she asked that someone if it was okay for her to pray for her lover and mentioned the date they became lovers.
This has nothing to do with her wanting or not wanting an abortion. This is very strictly and narrowly a question of whether or not someone is granted discretion not to prosecute two 17 yr olds who had sex the day before their 18th birthdays.
In statutory rape situations, the minor is not the one breaking the law. Only the adult is legally culpable.