What if her income improves? And even if it didn't, why would it be okay to permanently neuter people simply because they're poor?
Besides, you're making a presumption that it was because of carelessness. What if she made sure to use contraception and something went wrong? To abuse automotive analogies: you wouldn't ban someone from driving because someone rear-ended their car at a stop light, so why would it be okay to take away one of the most important aspects of life (reproductive ability) when it wasn't your fault?