Because it's a sign of MANLINESS to impregnate dames. If "the little woman" has 20 kids it shows how virile he is. Also pregnant women are always busy being pregnant and taking care of all those they give birth to. Every time after hubby dear makes sure to get her pregnant again. Why not? What else is she good for but sex and making babies so he can brag about it? So six weeks after having given birth he knocks her up again
Easy peasy. And so it goes. Sure some might die in giving birth so often like brood mares. So what? There are more dames out there to replace them. SIGH.