A student brought this article to my attention:
A biodemographical study of life span in pre-industrial Finland has provided evidence that boys are impose a longevity cost to their mothers (but not their fathers). In other words, the more boys a woman has, the shorter her lifespan. It has been posited that early reproductive effort might come at the cost of later survival and decreased later reproduction. This study is in accord with those ideas of reproductive tradeoffs. Why boys should be costlier than girls, though, is less clear. Here is the study: A trade-off between having many sons and shorter maternal post-reproductive survival in pre-industrial Finland (not open access).