Why stop there? A child about to be born is structurally and functionally identical to a child that has just been born. And once it is born, there are, as you say, "extremely negative consequences" to forcing the mother to either care for it herself or make other arrangements.
The right to dispose of any unwanted child the mother cannot or will not care for herself is one that, like in vivo abortion, women will exercise irrespective of whether the law permits it. Poor indigenous women in Brazil allow their sickly babies to starve all the time.
Conclusion: any society that does not allow humane infanticide within the first year is literally Handmaid's Tale.