Why would someone murder their own baby (or children)?

EDIT: I am by no means thinking that parents killing their children is ever justified, I just want to know the reasons why people do it because it's no breaking news that it has happened before. <br><br>I'm 14 (female) and I wish I could say I'm mature enough to watch the news (which I'm not) because I don't understand the world and all it's horrors. I'm not stupid I just can't comprehend why anyone would hurt a child when they should be the ones that are protected. (My little brother is only 7 and I would do anything to save him from harm). <br><br>I recently heard of a case where a mother drowned her three babies in a river. LIKE Wtf. None of them were even over 6 years old. <br><br>I would love it if someone could explain why people do this. Please don't call me immature for not knowing. This is the only place I can get any answers without being judged super harshly. <br><br>*Edit: You guys are amazing. Thank you for the responses. I have read them and they have helped me a lot. I didn't expect such kindness from the internet. Thank you <3*