A Study of Milk and Calcium Supplement Intake and Subsequent Preeclampsia in a Cohort of Pregnant Women

Abstract

To test the hypothesis that high calcium intake protects against preeclampsia, the relation between milk intake and preeclampsia was examined in a cohort of 9,291 pregnant women (7,104 white women and 2,187 black women) selected from the Child Health and Development Study population assembled by the University of California, Berkeley, during 1959-1966. Exposure was based on glasses of milk per day with and without calcium supplements. Data from both white and black women displayed a U-shaped distribution of preeclampsia risk in relation to milk and milk plus supplement intake. Logistic regression analysis showed that women who drank two glasses of milk per day had the lowest risk (reference category). The relative risk (RR) for those drinking one glass of milk per day was similarly low (RR = 1.2; 95 percent confidence interval (CI) 0.7-2.0), but risk for those drinking less than one glass of milk per day was substantially higher (RR = 1.9; 95 percent CI 1.2-2.9). Women drinking three or more glasses of milk per day also showed increased risk (RR = 2.0; 95 percent CI 1.2-3.4) as did those drinking four or more glasses per day (RR = 1.8; 95 percent CI 1.1-3.0). The increased risk associated with low milk intake is consistent with studies showing reduced blood pressure with increased calcium intake. The increased risk with high milk intake has not been demonstrated previously.