Parents disappointed? Advice?

My partner and I are in our 20s and ttc, and I found out a few days ago that I am in fact pregnant! (parents don't know yet) But its good news to us. However my parents are in their 60s, and think that if we have a child well be making a mistake & that we need to "enjoy our 20s" . My parents had me when they were in their 40s. We've both done our fair share of partying etc, and we've been ready to settle down for quite some time. We've been together for 4, almost 5 years. I know I shouldn't be so bothered by it but I'm just nervous as to what they'll think/ say. Any one else been in this situation?