Calcium absorption is highest during periods of intense growth, such as childhood and pregnancy, when rapidly growing bones have the highest demand for the mineral. With the exception of pregnancy, calcium absorption starts decreasing during adulthood and continues to decrease after menopause, when estrogen production declines. A lack of estrogen leads to more bone breakdown and less calcium absorption from foods and dietary supplements. This is why RDA for calcium consumption increases for women at age 51, the time menopause typically starts.*