The risk of DS after 40 is 1% like the other anon said.
https://www.stanfordchildrens.org/en/topic/default?id=pregnancy-over-age-30-90-P02481https://www.cdc.gov/ncbddd/birthdefects/downsyndrome/data.html>>77466>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4532312/This is a study about non-chromosomal anomalies (does not look into DS). Both under 20 and over 40 are associated with birth defects. There's also only one "over 40" category, which makes it hard to see how common birth defects really are in the 40s decade, although yes, the risk of some birth defects increases with age when they treat it as continuous (and for others decreases, and for yet others has a U-shape distribution). This does not disprove that women can give birth well into their 40s.
>https://academic.oup.com/humrep/article/19/7/1548/2356634?login=falseThis only shows that after 40 conception is more difficult, which is of course true, but still achievable by the majority within 4 years.
>https://journals.sagepub.com/doi/10.1136/jms.9.1.2This says the risk of DS does not increase linearly with age and actually declines in increase rate after 45.
>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3303492/Seems like having children later in live has both advantages and disadvantages, as anyone would expect. It's entirely up to each person to make their choice. This was a nice paper to read actually, showing how biology is not the end-all, be-all in the final choice.
>https://academic.oup.com/humupd/article/18/1/29/854296?login=falseAgain, logically both maternal and paternal advanced age are associated with more complications. The main takeaway "women have partners who are several years older than themselves and it is important to focus more on the combined effect of higher female and male age on infertility and reproductive outcome.". Seems logical, does not disprove what anon said. Maybe it's time for cougar milf takeover of young fertile men.
>https://www.tandfonline.com/doi/full/10.1080/00324728.2018.1442584>We find that across successive birth cohorts, the negative association between advanced maternal age and LBW becomes progressively weaker;This means that recently advanced maternal age does not have as much of an impact in child health as it had before.
>https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661791/This is about menopause, not sure what it has to do with child birth. Perhaps you linked it for the following
>It is estimated that natural fertility ceases on average 10 years before menopausewhich is true, the ovarian reserve starts depleting and making it harder to conceive, explaining the results of the previous studies. But also, most women in that age bracket can and do get pregnant, as we've seen above, it's simply less common.
>https://serval.unil.ch/resource/serval:BIB_19AEC7C94AAC.P001/REF.pdfShows women are having children later, but the time between pregnancies has decreased (the urge to have more children has more influence than the decrease in fertility as stated in the introduction).
It's important that women are well aware of the implications of their choices, but your bibliography dump was also misleading.