Low Calcium Intake in Midpregnancy Is Associated with Hypertension Development within 10 Years after Pregnancy: The Norwegian Mother and Child Cohort Study

Low dietary calcium intake may be a risk factor for hypertension, but studies conflict. We evaluated the ability to predict hypertension within 10 y after delivery based on calcium intake during midpregnancy. The Norwegian Mother and Child Cohort Study of women delivering in 2004-2009 was linked to the Norwegian Prescription Database (2004-2013) to ascertain antihypertensive medication usage >90 d after delivery. Women with hypertension before pregnancy were excluded, leaving 60,027 mothers for analyses. Age and energy-adjusted cubic splines evaluated dose-response curves, and Cox proportional hazard analyses evaluated HR and 95% CIs by calcium quartiles adjusting for 7 covariates. Analyses were stratified by gestational hypertension and by sodium-to-potassium intake ratio (