I don’t think this means what people think it does.
Considering IQ is at least mostly genetic (like, 70% charitably), and child IQ is based on the maternal IQ (not paternal).
Considering high IQ women marry and have children later (and always have done, historically, the average age of marriage in fact used to be around 25, earlier was reckless from immaturity, later was also fine hence remarriages were also allowed).
Considering they invest more money and time into their children, which accounts for the non-genetic factors to boot.
I think those factors all combine that there’s a third variable. Innate maternal IQ.
The age isn’t causing the intelligence in mothers to pop into existence out of nowhere.
Those women are intelligent to begin with, they delayed the gratification of family until they could support one and we’re seeing those women, responsible women, being compared with the spawn of the irresponsible and stupid.
Older mothers (very old, not, like, 30) either have very healthy babies or very sickly ones, it isn’t clear-cut always bad or always good. Either there are serious problems (a bad pregnancy, often ending in miscarriage) or there aren’t (a good one, biologically the same as a younger woman). Underage girls or young women also have a higher rate of miscarriage (and death) and disease/defects, although this is almost never mentioned. Nature evolved this for good reason, you can’t do things until their time and the reproductive system needs to stabilize hence this result shouldn’t be a surprising correlate. Your ovaries don’t start misfiring suddenly at an arbitrary age (although men, from the way they constantly produce sperm, DO have this high-mutation problem affecting the health and longevity of kids). The males of the manosphere, where you won’t see these studies covered because they’re bluepill pussies, have a lot of ridiculous notions of the female reproductive anatomy and function (e.g. they still talk about hymens like a seal on a tin can and making women bleed as a good thing). They can’t explain this stuff, in part because they think it’s “not their issue/problem”, “not science” and just “ew gross blood n stuff”, while expecting to be taken seriously as adults with internet access on reproductive topics. Naturally, if we try to educate them (you should be paying for this information), they’ll ignore you or call you wrong, because you ‘re a woman. Why would you know how a woman’s body works? That’s just silly.
It isn’t as if I’m trying to give them advice on ED, is it? (Although many of them are porn addicts, the true cause of ED). Everyone has their subjects. Random myths about ovaries and scare-mongering about fertility (while telling men to have kids while on Death’s door) are unhelpful. These people dole out dangerous advice to men (life-ruining, if you look at the cost of raising a special needs child) and have such a lack of class they mock women for their fertility problems and blame them for having a medical condition like PCOS (as if men don’t have fertility problems, when men have more fertility problems in total, mostly impotence issues and getting it up caused/exacerbated by porn use).
On the Eugenic Problem aka Idiocracy Problem.
If you want smart people to have children, they aren’t going to do it at age 18, it isn’t our way and never has been, so you’d better get used to later pregnancies. You can’t shame people into ignoring biology, like the feminists pushing fat as sexy. People always left it ‘late’ compared to the modern welfare baby at 15 ‘standard’. It isn’t too late until you can’t have any or if you refuse to have kids and become a genetic suicide.