In reply to Fay Kye Dee:
I had my first child when I was 40 and the second only 16 months later at 42. They are now 22 months and 6 months and both are perfectly healthy. I had no specific problems outside of the expected pregnancy niggles, sore back, fatigue etc. I do feel pretty tired these days, but I live in the US so am already back at work (they haven't cottoned on to maternity leave over here yet!). Not sure that the being tired is any worse at 42 than any mother with two kids under 2 would feel anyway. I do have recurring back pain, but that had started to be a problem several years before the pregnancies, though I think it's not helped by lifting the children ( I am very petite myself so they are quite a weight for me).
I did do some additional diagnostic tests in the pregnancy, pm me if you want details.
Good luck!