http://www.nature.com/news/having-sons-can-shorten-a-woman-s-life-expectancy-1.12516

I thought this article was interesting since I have a son and he is certainly more draining at the toddler stage than my DD ever was. Plus, it mentioned that having a daughter actually lengthened a mother's life (maybe cuz daughters tend to actually care for their parents more in old age?). It sounds like the results are not entirely conclusive or supported by any other studies, so this is just for fun!