Absorption of Dietary Calcium in Pregnancy

Abstract

Twenty-five calcium-balance studies were conducted on twelve subjects during their first, second, and third trimesters of pregnancy, on diets that provided about 400 mg calcium daily. Four subjects were in negative calcium balance during the first trimester of pregnancy. During the later stages of pregnancy, these four subjects came into positive balance without any change in the dietary intakes of calcium. In all the subjects, the amount of calcium retained during the second and third trimesters was significantly higher than that during the first trimester. The apparent absorption of calcium markedly increased during the second trimester and this increase was maintained throughout the third trimester of pregnancy. There was a reduction of urinary calcium in the third trimester.