This one is a tough call.
I think the "potential" dad has rights if he chooses to be present in the life of the child - with or without a relationship with the mother. If he just plans to parachute in once in awhile fleecing gifts or something, then he probably wants to just play dad compared to be one - in which case it'll be up to the mother involved in whether she feels it's beneficial.
Call me old fashioned, but I have a hard time believing a mother (without serious psychological or social problems) wouldn't want the baby after giving birth to it? It happens...I know, but still. I'm not sure that I could have a baby and just hand it over and forget about it.
I agree that when you consent to have sex - even while using birth control - you acknowledge that pregnancy is possible. If you choose to put yourself in that situation with a stranger...these unfortunate problems happen.
A friend of mine would say - it's the mother's body so she has veto power on terminating the pregnancy. I'm not so sure it's that black and white for me, so I just don't have sex with strangers - works for me!