I can only speak from my own experience. I'm 32 and I was born when my mum was 43.
There were a few issues relating to her age when I was growing up, but most of them boiled down to the fact that she's not a particularly warm, open or empathetic woman, and we're not close now.
The main issue was that, when I was a hormonal teen (nothing dreadful, just sometimes emotional), she was going through the menopause. I felt that her hormonal and emotional changes were prioritised above mine and that any hormonal outbursts I had were simply not allowed or acceptable, whereas hers were 'fine'. There is also the scientific position that women can sometimes lose their loving, more selfless sides after menopause, and I feel that this was true in her case, as she seemed totally disinterested in me from my early teens (not using this as yet another stick to beat menopausal women with, it's just my experience/what I have read!)
I'm now very close to my mother in law, who is 57, and I think perhaps my mother realises that this may be down to the fact that she has far more energy, and is much more open and friendly. My parents has extremely austere 1950s childhoods and I think they're often restricted by social conventions that only really exist in their heads now. An example of this was my wedding; they were a bit shocked at some of our non-traditional choices, which again just seems to accentuate the age difference between us.
I'm now trying to conceive myself and have to mentally fight back the feeling that I have left it too late myself. The main worry I have in addition is that my parents are now int heir mid 70s, are slowing down, starting to have little memory lapses. My brother lives 300 miles from them and doesn't drive; I'm 100 miles from them and do drive. I worry that I'll have to deal with small children AND increasingly vulnerable and frail parents (as many people do have to do) and that I'll lose them before I'm 40, just as I'd lost 3 grandparents by the age of 3, and all of them by 10.
None of this is meant as criticism, it's just my take on it.