Originally Posted by Inverarity
It's been implied that wizards tend to live longer than Muggles, but I don't think it's been implied anywhere that lifespans of 130 to 150 years are average, even for wizards.
Why wizards live longer than Muggles is debatable -- perhaps it's just that throughout history, they've been less susceptible to starvation, diseases and wars that would tend to shorten the average Muggle's lifespan. Or perhaps magic does extend one's life somewhat. But Dumbledore, who is over 100, is clearly no spring chicken, and he's also apparently older than the average wizard.
So I think having a witch giving birth in her 60s would be improbable. Extending the reproductive lifespan of wizards and witches would almost make them a separate species, and from what we've seen, they're humans, they just have somewhat longer average lifespans.