Jean-Baptiste Moheau, a remarkable yet obscure eighteenth-century French demographer, noted that "logic and a calculating mind would not lead to the propagation of the species." A rational view of children, Moheau recognized, would reveal the inordinate expense of raising them. For those who could afford them, children presented the risk that after all the efforts made for their education and formation, they would grow up to disappoint parents with their “disorderly conduct and their vices.”
Moheau believed that immoral couplings tended to result in few children, as the individuals involved took measures to avoid pregnancy or to abandon their newborn children: “A single girl who abandons herself to a forbidden relation will not add to the population, because debauchery does not breed; and she spoils the chances of the honest girl who would have had a husband if the enticement of libertinism had not taken him away from her.” Whereas Malthus assumed, at least in his rhetoric, that an unmarried woman remained chaste, Moheau worried that she ruined not only herself but also another woman’s happiness.
Jean-Baptiste Moheau, "Jean-Baptiste Moheau on the Moral Causes of Diminished Fertility," trans. Etienne van de Walle, Population and Development Review 26, no. 4 (December 2000): 821-826.