Yesterday I read an article on the potential link between stress and the sex of a baby. If you missed it, be sure to check it out. It was really quite interesting.
In a nutshell, researchers studied births in Chile from 2004 to 2006. They found that in 2005, when a major earthquake hit the country, the rate of male births decreased by 5.8%. They hypothesized that male fetuses may be more susceptible to maternal stress and there is an increased likelihood of miscarrying a male fetus when the mother is under stress.
An earlier study (long and scientific, but interesting) theorized that in addition to male fetuses being less capable of handing maternal stress, other factors might include stress causing a decreased sperm count in the father or when baby-making happens, making the couple more likely to conceive a girl.
So what does this mean for genealogists?
If the study's hypothesis is right, we may be able to use gaps in children to pinpoint time periods we need to research more thoroughly. While a gap generally is indicative of a miscarriage or child that passed young, it might also be a sign that the mother was under stress. Since females are also more likely to be conceived when stress is present, a string of female children may also indicate your ancestor's life was stressful.
We can then use this clue to dig a little deeper to find out why the mother was stressed. Perhaps there was a court case, illness, famine, local battle or death of a loved one that you hadn't found yet.