Earlier quoted context omitted.
It’s kinda implied that Sauron’s rings make individuals of the various races more interested in sticking around longer than in producing offspring. Hobbits were relatively unaffected and had lots of children.
But somehow, despite the fecundity of the Rosie Cotton-Gangees, with 13 children, the Shire had a total population of about 100k, the size of a small (edit: but not that small) town (or the UK population in 3000BC). So either pre-reproductive mortality is through the roof, but never mentioned, they haven't been there long[1], or something bad happened recently (before the events in the LoTR)[2]. [1] Except Hobbits se…
In medieval times, people had lots of children, but most of them died very young. Of course this doesn't fit into Tolkien's idyllic description of the Shire, so it's not mentioned, but I guess families with 13 children who all survived to adulthood were the lucky exception...