"Poverty, though it no doubt discourages, does not always prevent mar- riage. It seems even to be favourable to generation. A half-starved Highland woman frequently bears more than twenty children, while a pampered fine lady is often incapable of bearing any, and is generally exhausted by two or three. Barrenness, so frequent among women of fashion, is very rare among those of inferior station. Luxury in the fair sex, while it inflames perhaps the passion for enjoyment, seems always to weaken, and frequently to destroy altogether, the powers of generation."
[Link to searchable PDF](https://www.ibiblio.org/ml/libri/s/SmithA_WealthNations_p.pdf)
Smith goes on to talk about how the death rate for peasant children is much higher because they cannot afford to feed or care for their children as much as the wealthy can.
I feel like I have seen the idea of the infertility of noblewomen echoed elsewhere but I can't remember where. Was this just a persistent myth?
My Potential Explanations:
-Inbreeding among the noble class
-People with genes that made them bad at reproducing were given the best possible circumstances for reproduction and so those genes were able to propagate and build up in the population. This dovetails with inbreeding.
-Rich men spent more time paying for prostitutes and less time sleeping with their wives, especially after a couple pregnancies. Peasants could not afford to do so.
-Rich men got STDs like syphillis because they used prostitutes frequently which they then gave to their wives causing eventual infertility in one or both parties.
-Rich girls with rich fathers had more access to and knowledge of abortificants of the time. They also would lose much more value than a peasant girl if they were discovered to be pregnant before marriage. A common side effect of abortificants of the day was infertility.
Someone else may have a more historically grounded answer to this question, but it seems to me a great example of selection bias with a nice added dose of class and gender bias. Adam Smith has no data to make his claim, he is going by his own experience and cultural mythology. While Smith may know in his own social circle and perhaps through the social press of the day, a number of wealthy families that have not had children or have limited their childbearing for whatever reasons, he does not have direct experience with peasant families. When a family of wealth has no heirs everyone hears about it, but how likely is Adams to every have heard of any infertile peasants? It would be of no great news or interest to anyone in his class. So that is the selection bias -- his sample is skewed. And the added dose of gender and class bias is in the mythology of the fecund peasant woman who could give birth in the field threshing wheat and carry the baby home to cook dinner for the family. But in fact it is quite impossible for a half starved Highland woman to have 20 healthy children. That sentence alone should give you pause. How likely is a half starved woman to survive a single childbirth with a health baby, let alone 20 of them! A woman having 10 children and surviving was (and still is) a feat. 20 is an outrageous number. The fact that he can throw that ridiculous number out in a book he is writing as a economist shows how little he understood childbirth.
So I don't have the historical data to argue that Noble women had normal fertility levels, but I can tell you that peasant women did not have the kind of fertility Smith imagined here.