Unfortunately for this appealing idea, “There is no evidence that these foods contain toxins in amounts that would cause birth defects,” says Dr. Richard Johnston of the March of Dimes. So why is there morning sickness? Hormonal changes alter blood vessels from the nose to the gastrointestinal tract, making women sensitive to smells and subject to nausea. “It seems plausible that food aversions are side effects of these hormone changes,” says Johnston. “There’s no need to suppose that [morning sickness] confers an evolutionary advantage.” Or that if you eat cabbage while pregnant your baby will be deformed.
