My wife is a labor nurse who sees patients of all shapes, sizes, ethnicities, and ages. Based on her 8 years of delivering babies at large and small hospitals all over the country (we travel for work), I can say the following with complete confidence (albeit, second hand): 
Yes, younger people are more fertile. 
Yes, some ethnicities are more fertile.
Yes, more problems arise in AMA patients (that’s “advanced maternal age”).
Yes, some people are the exception to any bit of research you can find.
Sadly, some women are not biologically capable of creating life.
Sadly, some women are TOO capable of creating life that they don’t want.
Ironically, many women only get pregnant after they stop trying.

I would suggest ignoring what anyone with celebrity status or a lot of money does. They have near limitless money and resources, and for every 45 year old pregnant with twins you read about in People magazine, there are likely dozens (or more) of disappointed women throwing away another negative EPT — they have no intention of sharing that story unless they need a new PR spin.

My wife and I are both 30, and have a high probability of not being able to have our own children for various reasons. In that case, we will definitely adopt over any sort of medical intervention; however, the entire adoption process is a mess of bureaucracy and stupidity. We’ve also always felt that multiple miscarriages is the body’s way of telling you that pregnancy might not be in your best interest, but completely understand the desire to keep trying.