[ArtemisPanthar]

I feel that there are more viable reasons than just potentially fatal childbirth or severe birth defects. Lets try a hypothetical:

A relatively poor working class single-mother has three children and currently works 2-3 jobs in order to be able to afford the cost of living. They live paycheck-to-paycheck with little wiggle room, but they're happy and want for nothing. Then the woman gets pregnant. It could be for any reason - carelessness, malfunctioning contraception, rape/coercion, anything. But it happened and now she's pregnant. There's no way she could afford another child, she knows this. But there's a bigger problem. Pregnancy is taxing on the body, eventually she may not be able to work by the end of her pregnancy, but not working means she couldn't afford food or shelter for her family. Maternity leave isn't always with-pay, especially for less-than-legal establishments, and although there are laws meant to protect mothers some places do fire employees who get pregnant. Additionally, the woman is at risk for pregnancy-related illness like toxemia which, while it isn't fatal, requires her to be on strict bedrest for weeks/months prior to the birth. Weeks/months she won't be having any income.
The father has disappeared/gotten arrested/whatever, so he can't 'help' and the woman has no family able/willing to help her. The government can't provide enough money to cover the woman and her three children and there's a big possibility they will take her children from her.

What does she do?