Yeah. It's always better, when killing a baby, to have it not feel pain. "Hey mom. We killed our baby today, but not to worry. We anesthetized it first, just like you'd do a dog or cat." I guess you're OK with that. Sad.
You did not address this, so I'll leave it up.
Get raped and become pregnant. Be molested by your uncle and get pregnant. Get pregnant with your fourth child and watch your partner/husband leave you for someone else. Use three forms of birth control correctly but still end up pregnant. Now what?
In your world, you anesthetize and then kill the baby.
Pregnancies from rape/incest are very rare. Using three forms of birth control and becoming pregnant is very rare. As to the mom whose husband left her, would you be OK with killing the oldest child and then giving birth? That way, at least all of the children could enjoy a somewhat brief life. Are you OK with that? We could be sure to anesthetize the older child lest he/she feel any pain from being killed. For that matter, the mom could have all of the born children anesthetized and killed, and then she could give birth and have only one child. Sound reasonable? I mean, if we are OK with killing human beings, then what difference does it make how old they are?