Pregnant at 40. I want my ob go refer me to a specialist clinic just in case. What will he think of that?

Hard to tell. An ob/gyn is a specialist, trained to care for pregnant women - at any and all ages. They are trained to know when to refer patients to a high risk clinic. Most ob/gyn's are not going to be offended when their patient asks for a referral, but that is possible. You just have to be able to talk to your doctor - and you need to be comfortable with your care.