Great expectations

FROM the compelling (don’t smoke) to the flaky (stay out of saunas), pregnant women hear a lot of advice about what is best for the little creature kicking inside them. Nearly everybody knows that it is bad for the fetus if the mother is starving or sick, and that exposure to toxins during pregnancy can cause a baby to be born ill, early or small. Now the evidence is piling up that subtle or short-term harms suffered by expectant mothers can affect their children several decades later—even when they are born full-term and of normal weight and apparently healthy (see ).Some of the best evidence for this “fetal-origins hypothesis” comes from historical disasters. By looking at what happened to babies who were in the womb during an epidemic, a famine or an environmental calamity, and comparing them with those born a little earlier or later, researchers can disentangle the intertwined influences of genes, upbringing and the prenatal environment. Recent studies have looked at the long shadows cast by catastrophes such as the influenza pandemic of 1918, the Dutch “hunger winter” of 1944-45 and radiation from the Chernobyl nuclear meltdown. The consequences for unborn babies were visible years later. They did worse in school, earned less money and were more likely to be ill.