32 and wanting!!

Me and my husband have been married for 2 years now, I'm 32 and would really want to start having some kids! My husband on the other hand is very ...I'm gonna say "scared" I don't know what else to call it. I hate to be a nag every month and beg him but I'm not getting any younger here!! When I ask he says he still wants kids, but won't confined into what's holding him back...any insite?