Chocolate, especially dark chocolate, is rich in a chemical called theobromine, which stimulates the heart, relaxes smooth muscle and dilates blood vessels, and has been used to treat chest pain, high blood pressure, and hardening of the arteries, Dr. Elizabeth W. Triche of Yale University in New Haven, Connecticut and colleagues write.
Preeclampsia, in which blood pressure spikes during pregnancy while excess protein is released into the urine, has many features in common with heart disease, the researchers add.
To investigate whether chocolate's possible cardiovascular benefits also might help prevent preeclampsia, the researchers looked at 2,291 women who delivered a single infant, and asked them about how much chocolate they consumed in their first and third trimesters. The researchers also tested levels of theobromine in infants' umbilical cord blood.
Women who consumed the most chocolate and those whose infants had the highest concentration of theobromine in their cord blood were the least likely to develop preeclampsia. Women in the highest quarter for cord blood theobromine were 69 percent less likely to develop the complication than those in the lowest quarter.