Further to what a few posters have said. DD has a couple of friends who are close to her age - early to mid 20s - and they were both born to older parents. One girl (Lizzie) was born to a 45 y.o. mother and 53 y.o. father - (natural conception, only child.)
Her whole time of growing up she felt embarrassed by them looking, and acting old enough to be her grandparents, and yes, like in some cases mentioned on here, she was bullied for it. I know people will blab the old chestnut 'people are bullied for lots of things' but so what?! 
She got to 18 y.o and her parents hit 63 and 71, and her dad became ill and went downhill very quickly, and could no longer leave the house alone, or drive. Her mum became his carer. Then within 6 months their mum had a stroke, and they were both housebound; couldn't get to appointments, or do their shopping, struggled with cleaning the house/doing the washing etc. So Lizzie ended up being the sole carer of them both at NINETEEN!
She had to drop out of her university degree, and become their full time carer. At 25 she still is. She does everything for them. She has NO LIFE of her own, and has not had for 6 years. The time when she should have been at university, travelling, building a career, partying, and going out with her mates, she is full time carer to her parents ...an elderly and infirm couple.
As a pp said, it wouldn't be so bad if there were older siblings, because at least when the parents' health declines (when the kid is still teens or early 20s,) there are older siblings to share the load.. And also older siblings will be there when the child born to a 45 y.o. mother loses her parents at a young age.
Another girl (Sarah,) who is friends with my DD, was born to a 46 y.o. mother, and a 50 y.o. father. (IVF.) Both her parents died when she was 22 (when her mum was 68 and her dad was 72.) Just 5 months apart.
She is also an 'only,' and had to deal with THAT with no siblings for support, no grandparents, and both parents dead, whilst still was in her early 20s. She also had to deal with both funerals at the age of 22!
Anyone who thinks having their first (and probably ONLY child) past the age of 41-42 needs to give their head a wobble. Seriously, it's not all about you. You need to think outside the box and think not about how old YOU are now, and how FIT you feel at 45/46, and how you can EASILY cope with a baby. It's about how old you will be when that 'baby' is a teenager, and the fact that when they are in their 20s you could be infirm and needing care, or possibly not here anymore...
And also the fact that you will be in your early to mid FIFTIES when they are at primary school. If that ain't weird and uncomfortable for a little kid (whose friends parents are mostly 25 to 35 ish,) then I don't know what is
I know several more young people in their mid teens to mid 20s who have a 70 to 75 year old dad, and mums in their late 60s. It's just weird and wrong IMO.
And yeah I KNOW people can have a baby at 28, and still die at 51 when the child is only 23, and leave them behind, OR have a baby at 29 and become very ill and infirm at 50 when the child is only 21. But that is a LOT less likely than if you have your baby in the bloody mid 40s!