I can see where the defense counsel might have felt such a jury would be more sympathetic to a parent who felt overwhelmed where women who hadn't had children yet could be presumed to suffer from mothering instincts without the experience of child-rearing. Let's face it, kids can be utterly exasperating and can move fast when you least want them to. Not sure about the operative theory WRT eliminating guys from the jury other than heterosexual guys being less empathetic (and you have to admit there's some truth there).