As many have already pointed out, you're very wide of the mark. In the past, before birth control was more readily available, it was normal woman to be having their 5th, 6th + babies well into their 40s. These days, a lot of woman won't even start trying for a baby until post 35 for a variety of reasons (career, not met the right person yet, not even sure whether they want to bring children into this world until then etc). Then fertility issues can easily mean it takes several years to get a viable pregnancy, if at all, meaning it's not unusual at all for women to be pregnant at 40+. IVF makes it possible for woman to fulfil their dreams of motherhood later in life too.
I teach Reception. Id say at least half of the mums of children in my class are early-mid 40s now, meaning they gave birth in their late 30s, possibly even early 40s. For several of them, their Reception child is their eldest. Not that it means anything in terms of this thread, but several of the dads look around 50ish. People are generally starting families much later now.
I personally know 4 people who are 37+ who gave birth within the last year. Two had their 1st child, two their 3rd. The two who had their 3rd last year didn't have any of their children under the age of 30. Both of the people who had their first last year at 37+ have made it known they would like more children, if they can.
Yes this is a small sample of people in the grand scheme of things but it's a growing pattern in general. You'd have to be walking around with your eyes shut to not realise many people are still childless at 35 these days, for various reasons, and it's not at all uncommon for women to still be producing children into their 40s (varying from much longed for miracle babies, totally unexpected ooops blessings and everything in between).