Thomas Jefferson wrote to the profitability of breeding female slaves to George Washington, telling him where to invest his money. It the case of Virginia plantation owners (and elsewhere) it wasn’t a case of slave breeding or unpaid labor. They got both.

“I consider a woman who brings a child every two years as more profitable than the best man of the farm, what she produces is an addition to the capital, while his labors disappear in mere consumption.” — Thomas Jefferson.