As bizarre as it sounds, I think the woman holds more "say" in it. I agree that the man's opinion is valuable, and those similarities in legal terms etc are valid too.
The thing is 9 months is a fucking long time. It involves a constant sick feeling. You get bigger: employers, peers, teachers parents etc see a pregnant young teenager - its quiet "humiliation" (if you want me to elabourate that, please say so).
Life becomes harder - constant interruptions meaning that going to school or going to work becomes almost impossible. She then makes more sacrafices than a man does, where he doesn't get huge, doesn't get silently looked down upon and forced to give up work or school.
It's much the same value as your parents word about what you should do with your life - it's valid, but to a degree.