Need advice.. I’ve been with my boyfriend for a few months and have just found out I’m 4 weeks…

Need advice..

I’ve been with my boyfriend for a few months and have just found out I’m 4 weeks pregnant. I’ve told him about the pregnancy and he hasn’t taken it so lightly, he’s adamant he isn’t ready and suggests we abort the pregnancy. (We both don’t have any children)

I’ve always been against abortion and feel I’d regret it if I ever did it. How do I explain to him that I can’t do that without seeming selfish?