If you're a woman with a healthy pregnancy I don't think parsley will necessarily cause abortion, however, this really should not be tried either way!!
If you really want to abort your baby, for whatever reason, you should talk to a trained medical professional who will offer counseling and assistance.
This is such a huge step, and one that you have to live with for the rest of your life. I have a friend who aborted a baby 20 years ago and thinks of it every day.
I am not saying abortion is wrong, it is a very personal thing and if it is right for you then you have the right to make that decision, but please don't use some old wives remedy to do this. See a doctor, talk it through with them ,and if you want to go ahead with it, do it the proper, tried and tested medical way.
Otherwise, you could end up harming yourself and the baby, with catastrophic results!
If a medically supervised abortion isn't an option (in some countries it can be very expensive or even illegal), then maybe adoption is something you could consider? There are so many couples out there who can't have children of their own and would welcome the chance.
Whatever you decide, I wish you the best of luck.