I'm sorry, but I think this is utter bollocks.
When I was 25, it felt hurtful and patronising that certain idiots imagined most young women had no idea about their biological clocks, because (like a lot of people on this thread), I wasn't in the least unaware, I was just struggling.
And now I am older, I feel even less like telling 25-year-olds to hurry up and have babies.
They know.
There may be a few women who genuinely have never, ever, ever, ever been told that fertility declines with age. Women who've never seen a Daily Mail sadface headline or stumbled over a magazine article or seen the innumerable threads on mumsnet and facebook and so on. But the number must be vanishingly small.
What most people who're infertile in their 40s are dealing with is either 1) yes, I wanted a baby and I tried to have one and it didn't happen in my 20s/30s and it's not happening in my 40s either, or 2) yes, I wanted a baby but life is complicated and I wasn't in a position to try before.
Neither of those are positions that are helped by people preaching about biological clocks or pretending women are stupid.