True - but, honest question that I've always wondered: Do we know the degree of this problem as it relates to whether or not people have kids? I.e. yes, it takes longer to get pregnant, but how much less likely does it become to get pregnant at all?

Nearly every metric gets worse

- likelihood to get pregnant

- likelihood to bring child to term

- health risk to mother during pregnancy and child birth

- health risk to baby during pregnancy and child birth

- increased likelihood of multiple birth defects

- increased likelihood of genetic abnormalities

I'm not casting aspersions. My wife and I had kids when she was 38 and 40 respectively. But, the numbers for the risks are stark.

So even if it takes a year instead of one night to get pregnant, which wouldn't really affect long-scale statistics that much, more pregnancies fail, and more people may choose not to try at all because of the risks. That makes sense.

It's got an effect but agreed it's not the biggest effect given what else is going on. I think time might be the bigger factor here when simply discussing biology. If you have kids every ~3 years and don't start until you're 35, you have maybe 1.75 years of kids left in you before it starts getting tenuous. (ie, before the woman is over 40) That same math works out differently if your first kid is at 20.

None of this touches on industrialization and higher education, which seem to be the more universal effects, even if one of their bigger effects is merely to delay motherhood.

That or go "one and done" after having enough fun with:

- Stress on the relationship of trying and failing for a long time - Stress of fertility treatments, if needed - Likelihood of dealing with inevitable miscarriages on the way to a birth - Overall "medicalization" of pregnancy in middle age, and the stress of all that contact with the medical system

Yes it would, because if you don't start until you are 30, you've "lost" a decade of childbearing. That's a pretty serious reduction in the maximum number of children you are likely to produce.

Also if you're 22 and chasing after a toddler, having more kids is going to be much more reasonable-sounding than if you're 32 or 42 doing the same.

Kids is fast.

How many do you want? 2 is quite normal, are you saying you'd only be able to have 3 maximum (but 2 in reality) instead of 12 maximum (but 2 in reality) or what?

No need to gender this, and I feel like people would be more receptive to the issue if it wasn't. Everybody ages: https://pubmed.ncbi.nlm.nih.gov/12801554/

Your source doesn't contradict the fact that women's fertility has a sharper and earlier cliff than men's. It doesn't even use the same age brackets for men and women. It compares men age over 45 against men age under 25, whereas for women the study compared those age > 35 vs age < 25.

Even above age 35, 85% of men are able to conceive within 12 months: https://pmc.ncbi.nlm.nih.gov/articles/PMC11026002/

Like it or not, fertility decline is substantially different between the sexes.

Gender does matter though. Men can sire offspring into their 60s, women have marked decline in fertility starting from 32 and hit an absolute wall (menopause) by their fifties.

Men can sire offspring into their 60s but not without some increased risk of undesirable outcomes such as their kid having schizophrenia https://en.wikipedia.org/wiki/Paternal_age_effect

Men offspring-ing in their 60's and dying 10 years later is perfect way to build a society where kids get to grow up without their fathers when they need them the most

Then again, they inherit a nice house at the beginning of their adulthood instead of being a landlord's squeezed client for decades.

There are trade-offs everywhere.

People forget that there's been a multi generational messaging of preventing women from having kids without economic security; this used to be done by the parents rejecting marriages that didn't bring enough dowry and extreme punishment for extra-marital relationships.

Now contraception has decoupled these things. You can have the relationship you want, and put off children until "sufficient" economic conditions have been reached.

(It is good news that India is at or below replacement rate! The conversation would be very different if in a few decades time India had to find twice as much food and oil!)

> People forget that there's been a multi generational messaging of preventing women from having kids without economic security

I think it's probably a wise thing to advise against having children you can't afford to take care of. I don't think it was something that was explicitly hammered into me or my peers growing up, but we all saw enough examples of kids being raised in poverty to know that we wanted something better for our own children.

It's not just women either. The older the father is the more you get risks for certain things like mental illness in the child https://en.wikipedia.org/wiki/Paternal_age_effect

Yes, but it's a false equivalence.

A 60 year old man can reliably have children. It is essentially impossible for a 60 year old woman to have children. The risk of defects from poor sperm increase from about 2% in your twenties to 4% in your sixties.

However, men do have a biological clock and that clock is simply that they are proxied to women's clocks. Mick Jagger can get a young girlfriend and have babies in his old age because he is famous with lots of money. The typical man cannot do this and should not plan on being able to do this. The data tells us that if a man reaches 45 without children, it is extremely unlikely that he will ever have kids, even if his sperm tests perfectly in the lab.

> Also, women's overall fertility drops off a cliff after 30

Men's too, from 40s up. Not as severe, and not cliff-like in the end like menopause. But it compounds, as the typical couple ages are directly correlated.