They don't really know the full implications of having kids after 40. Downs and autism risk are definitely higher. Our shit pseudo-health system is really bad at doing long-term tracking of this kind of stuff both because its more and more operated by pajeets and other retards and also because any data to suggest women should spend their healthiest and most fertile years focused on their families would run counter to the interest of our corporate overlords who want us assured that post-40 parenting is totally fine. BTW, theres increased risk if *either* parent is above 40. Men are also more likely to have "weak" / mutated seed after 40. The effect is less severe for men than women though.