Excerpt:
I had my first child when I was 36 years old, which made me want to understand the risks of having children at different ages. Before looking into this, my impression was that the main biological problems with old-age parenthood had to do with not having the necessary health and vigor to care for young’uns, and I had heard that older women have trouble getting pregnant. While those are real issues, there are many others worthy of consideration.
My read of the evidence is that the risks of miscarriage and serious health problems for children, including autism and birth defects, increase significantly with parental (both paternal and maternal) age. The data I could find for most risks is not very fine-grained and not very precise, but I think this qualitative description matches the data: Risks start rising at around 30 years old for both mothers and fathers, rises gradually through about 35 for mothers and 40 for fathers, and then sharply after that.
One more problem: no help from grandmothers.
Younger parents can expect being helped by their own parents in babysitting, cleaning, money etc. Older parents are on their own as their parents are already either dead or too old to help.
This observation is based on personal experience.
My understanding goes along similar lines, so I’m not highly doubtful. If anything, I’ve had the idea that the risk of developmental disorders and miscarriage, difficulties in getting pregnant and some pregnancy related issues might begin rising substantially much sooner than in one’s 30s.
To me it seems that the overwhelming majority of children conceived even after 35 are all healthy and fine. That is, >99% on autism, >98% on chromosome disorders. The risk of miscarriage is relevant. All these considered, I believe this evidence means people should likely not be too worried whether they are already too old to have kids.
Whether or not having kids earlier might still be better, while accounting for the costs on one’s career or business, etc. is another discussion, particularly when thinking of large numbers of people. However, AFAIK a lot of people already want to conceive while they are young, and I’m not sure whether people considering trying kids can significantly be swayed one way or another by this evidence alone.
(comment edited: missed the link at first sight)
The “sharp increase or risks” seems correct but is a bit misleading.
For paternal risks, there is indeed an big relative increase “14% higher odds of premature birth” (https://www.bmj.com/content/363/bmj.k4372). But in absolute terms, I would not think of the increase as huge: from ~6% ( based on quick googling) to ~6*1.14=6.84%.
IMO ~1% increase in risks is not something to be concerned about.
Not sure if you saw the full post at the link, but some absolute risks, such as for miscarriage, are much higher. And for me personally a 1% risk of having a child with a serious mental disability is really scary. Perhaps not for you.
Down syndrome
I believe down syndrome is caused by a chromosome disorder, which is covered in the blog post. Risk does indeed rise sharply with maternal age past ~35.