Evolutionary biologist Virpi Lummaa has discovered that Finnish women in previous generations suffered a variety of adverse effects when they bore and raised sons.
Among the impacts: a reduced lifespan, greater vulnerability to disease due to higher testosterone exposure during pregnancy, daughters who were less likely to reproduce, and smaller subsequent children. Additionally, having a grandmother around was more helpful than having a grandfather (probably because she helped with childrearing while he just sat around and ate food).
While modern reproductive technologies have mitigated a lot of the effects seen in pre-industrial families, it is still intriguing to consider these impacts in light of the strong cultural bias favoring the bearing of sons. Perhaps it is a type of "peacock effect", whereby the individuals who still thrive in the face of handicapping or indulging in risky behavior are considered stronger and more robust. Or, as my mother asserts, the value balances out an apparent difference in general robustness and health between male and female young, where males often are weaker to start with.
Of course, having too many sons can be evolutionarily disadvantageous too...