Imagine a very wealthy gay couple of two men selecting a biological mother for their single future child. They have 18 otherwise very similar healthy women who have agreed, they only differ in their ages and are from 18 to 35 years old, with each age represented once. They’ll pay the woman a million dollars and the baby will be adopted completely by the couple, with the mother relinquishing all parental rights and obligations to them. They are trying to figure out which woman would be best as to minimize any potential biological, physiological and other harm to the child and the mother during and after the pregnancy and childbirth. So which woman do they choose?
Ignore things like how the pregnancy would effect the woman’s life in other ways, like an 18 year old might have to graduate later if they get pregnant in high school, or a 35 year old might have to take days off from work etc. The things that I’m interested are related to:
a) the risk of the mother’s age on the child not being stillborn, premature, having any birth defects, having a disability etc.
b) the risk the mother’s age on any pregnancy related health effects like pre-eclampsia, postpartum depression, death etc.
Other factors are also important, like chance of the women getting pregnant in the first place: the higher the chance, the less expensive and/or time consuming the process will be.
A graph like the one below exists for Down syndrome. Any other graphs like it would be neat, especially one that combines multiple (or all) risk factors. Any other insight or data would be swell too. It would have to contain the women’s ages from 18 to 35 though!
Definitely before 30. Probably before 25. Not sure where “too young” would kick in, but assume the woman is entirely through puberty AND finished growing 18 would be older than that. But some women are late bloomers. I think the preference is at least two years past physical maturity? So… 20-25 to be on the safe side.
There are certain physical results of pregnancy that will just happen in some cases and can’t be fixed. One example is urinary incontinence. 1 in 3 mothers experience it, not sure for how many it is permanent. Another is gestational diabetes, which is sometimes permanent. So, my point is that the closest you can come to mitigating these problems is to lower the number of years she will have to deal with it. I don’t think it is in any way optimal to start dealing with that at 17 instead of at 30.
So, I’d say the oldest age at which you don’t see proof of accelerated risk to mother or child, is the age you are aiming for here.
Right after the end of puberty (however that’s determined). The number of viable eggs is highest at birth and declines continually throughout life. So the optimal age (biologically) is right after puberty, when the musculoskeletal system (particularly the pelvis) is as big as it’s ever going to get, and the ovarian reserve has the least chromosomal damage.
Of course there are many other reasons other than biology why 17-year-old mothers don’t have ideal life outcomes. But your OP specified that we ignore that, so I’m ignoring it.
I read a study of young mothers that looked at married middle-class Mormon women, and found that there were more health problems and more premature births (and fewer pregnancies) with teenage moms. No, I’m sure i can’t dig up that study today. But the authors hypothesized that teenagers are still growing themselves, and their growing bodies competed with the fetus for nutrients.
So I’m going to guess 22-25 is ideal. Maybe 20-25.
I’m also going to speculate that the curve is very flat in that range, and there probably isn’t a statistically significant best age among those ages.
By the way, the point of that study was to test the hypothesis that the reason pregnancy outcomes for teen mothers are poor is because teenagers who get pregnant have other problems. So they looked for a group of healthy, socially supported, adequately fed, health-insured teenage moms. And they still found that their pregnancies had more problems than those of slightly older mothers.
I’m going to point out that the OP wants us to optimize 3 variables: best health outcome for baby, best health outcome for mother, and best likelihood of getting pregnant quickly/easily.
I think it’s fair to say there are different ages for the mother for each of those three optimals. E.g. some IMO reasonable WAGs here:
For the baby, Mom age 23 is optimal.
For the mother, Mom age 32 is optimal.
For getting pregnant easily, Mom age 14 is optimal.
So until / unless the OP tells us how he wants to trade off those three variables, we have an insoluble math problem regardless of whether we can solve the biostatistics problem of what real values correctly replace my WAGs.
As @Chronos almost said just above, if the three values aren’t too dissimilar, it doesn’t much matter how we mathematically blend them to the get a single optimal. To the degree the spread is larger, or the steepness of any of the 3 curves is significant, the math is less forgiving.
That’s not true. Teenage girls are a less fertile than slightly older women. It’s really hard to find figures for women under 20, but i found this:
“The odds of conceiving in a given year are about 75% at age 30—but if you’re a teenager, it’s 90%,” she says. “Women are most fertile from ages 13 to 30. That’s reproductive prime, with 18 to 25 being the peak.”
I have read elsewhere that young teens, menarche to 16 or so, get pregnant a lot less than would be expected if they were as fertile as 18 year olds, but i couldn’t find any hard numbers.
I was able to find a reference to teens having less healthy pregnancies. It says that a lot of the difference is due to social factors, but did find some differences that persisted even in countries that minimized other problems, notably low birth weight
There is a very marked association between young age of mother and low birth weight in all countries.
and
Late fetal death rates in the United States, England and Wales, and France are slightly higher among teenagers than among women in their 20s. In Canada and Sweden, however, no substantially increased risk for young women is found.
Good info. Thank you. As I said, those were WAGs to demonstrate a mathematical point.
I would certainly expect that problematic pregnancies (and maybe miscarriages) are common in the early post-menarche years. I’ve certainly read of the problem with very young mothers producing low birth-weight kids. The optimal age for producing a healthy baby is later for just those reasons. But that wasn’t what the OP was asking about.
An interesting question I don’t know anything about is how the ever-earlier age of sexual maturity in young women may be changing things.
At the same time women (at least first world non-poor women) now have more opportunity for good nutrition and exercise and medical care throughout their early life and teenagerhood. Such that they end up larger, more robust, and may keep growing a bit later than what was typical 1000 years ago. So are women becoming “fully grown” later, earlier, or no change? Heck if I know.
The general thought is that intelligence is about 50% heredity, so I would suggest that perhaps that should be a factor if they are looking for a child who will be moredately smart. I assume “equally healthy” criteria then applies to the general genetic qualities of the mother.
Although I lived for a while in a small town where, in the 1980’s, it seemed that girls 15 to 20 had no difficulty getting pregnant.
My niece is an OB-GYN and based upon her studies it was age 24. Thus she and her husband had their first child when she was 24, while in medical school.
That’s all well and good trying to choose the best age bracket to impregnate a surrogate but the wealthy gay couple should also consider their own paternal age for producing the most genetically robust sperm into that surrogate. 21-38 years old is the recommended best age for men.
