That's a good question, made me click right away. You see supposedly pregnant women are responsible enough to decide for their kid because well under some circumstances they are responsible for their bodies and or don't want them or the baby to suffer due to them not being able to give him shelter or afford a kid. But then again you get to decide for someone who wasn't even born yet. You're not a human being, you practically belong to someone else, you're just a notion, an idea, a fetus, just something. But when you try to kill yourself you're responsible enough for your life therefore you aren't "allowed" to do that. Hence the difference.