Perhaps you've heard about the prospective parents trying to time pregnancies according to the school year (aiming to make kids among the oldest in their class)? Now they may be aiming for specific birth months in order to give their offspring the best chance for optimal health. A new study shows that babies born in May have a much lower risk of disease than those born in November. Although speculation for these differences abounds—i.e. building up greater vitamin D stores in the first summer of one's life may have protective effects—no causality has been determined. Since we can't go back in time, there's nothing we can do to improve our own birth months. But we can, however, get busy with the baby-making in the lazy days of August.