Nutrition: Too Much of a Good Thing

Aware that she is "eating for two," a pregnant woman is likely to make sure she gets sufficient bread, cereals and milk—all of which, because of the long campaign to wipe out rickets, are usually fortified with vitamin D. Her obstetrician may well prescribe a daily capsule of supplemental calcium and vitamin D. And while the mother-to-be is taking it easy, she may do a little sunbathing, which stimulates her system to make still more vitamin D. It all adds up not only to a hefty dose of the vital vitamin but to some risk that her baby will have...