Harelips and webbed feet were blamed on encounters with belligerent hares or angry ducks. The sight of a slaughtered animal falling to the ground was believed to cause epilepsy. Even a longing for particular foodstuffs was considered potentially damaging during pregnancy. It is interesting to note the link between people's eating habits and their responses to birthmarks - in England, eating too many strawberries was commonly blamed for red blotches on a newborn baby's skin; while American folklore from Utah mentions marks shaped like bacon, or even a roasted broiler.
Canny women used the theory of maternal impression to their own advantage.
Madeleine d'Auvermont had some explaining to do in 1637 when she gave birth to a healthy son - for her husband, a French nobleman, had been abroad for four years. Brought to trial for adultery Madeleine insisted that her longing for her absent spouse had been so great that the child had been conceived by the power of her imagination. Medical and theological experts agreed that this was entirely possible, so the child was pronounced legitimate.
In 1726 Mary Toft, a country lass from Godalming, Surrey, convinced King George I, and a host of learned gentlemen including the court anatomist, that she had given birth to 17 rabbits. She became an instant celebrity - so much so that collections of "rabbit woman" pamphlets and ballads were still highly prized a century after she was declared an opportunist and an impostor, who had simply hidden a sack of freshly-skinned bunnies under her skirt while "in labour".
Superstitions surrounding maternal impressions have died hard. As recently as 1981, a study of popular beliefs concerning facial deformities found that more than 20 per cent of those interviewed believed "port wine" stains on newborn babies were due to the mother's craving for strawberries or red cabbage.
More disturbingly, telegony (the belief that influences from earlier conceptions will recur) became a pet theory of racists and anti-Semites.
Nazi propagandists, for example, held that a German woman "defiled" by a Jew or a Negro could never give birth to a child of "pure" blood again.