If you were of high class like the nobility or mercantile, you had children to continue your powerful bloodline. You also married to sign off on alliances and c

If you were of high class like the nobility or mercantile, you had children to continue your powerful bloodline. You also married to sign off on alliances and cooperatives. Entire wars have been waged over familial ties and successors. If you were of low class like the peasantry, you had children to have enough hands to till the fields. If you were of middle class somewhere in-between, you had children for both of the above each to lesser degrees. In the modern era there's simply less and less practical reasons to have children, not to mention the costs of childcare and rearing. On the bright side, at least we have less instances of war being waged because Lord Dickus Bigus wants to pork out on a lady and screw everyone else.