Evaluation of the relationship of sodium in drinking water and toxemia of pregnancy.

This study is a retrospective case comparison analysis of the relationship of water-borne Na+ and toxemia of pregnancy as a part of a continuous investigation at our facility on the role of various water constituents in human chronic disease. Five hundred thirty-seven toxemic pregnant women delivered at Jefferson Davis Hospital, Houston, Texas, during 1976 were matched by age, race, obstetrical history, and month of delivery to 537 non-toxemic controls. Sodium concentration in each patient's drinking water was derived, based on her address, from earlier prepared maps of sodium distribution in Houston's water supplies. Paired t-tests were performed to compare the Na+ levels, which varied from 19 to 250 mg/l in water supplies of cases and controls. Odds ratio analysis was used to test for the presence of a gradient in occurrence of toxemia in parallel with the gradient of Na+. No significant impact of water-borne Na+ in the indicated range was observed. Further studies incorporating still higher ranges are contemplated.