I had 3 in my 20s and have just had no.4 at 45 
I don't feel any different now compared to then, and honestly none of my anti or post natal health care team turned a hair at my age. Those who i actually asked said it was quite common now to see women in their 40s due to the rise in 'second families' these days.
The general consensus from them was if you are resonably healthy and have no history of hellish pregnancies then your body knows what it's doing and will do what nature built it to do. I was left to get on with it more or less - seen less often than was routine in the 90s when i was under 30.
Obviously there are risks in pregnancy for - which do increase as you age - but frankly they start to rocket after your late 20s anyway
- so ... if you're really going to take notice of risk assessment figures then you can consider yourself past 'optimal breeding age' by 29!!