Study on the Metabolism of Nitrogen, Calcium and Phosphorus during Pregnancy and Early Lactation

It is necessary to know the requirements of N, Ca and P for fetus in order to discuss about the metabolism of these elements during pregnancy.Since the amount of each chemical component contained in the fetus could be considered as his requirement for these nutritional elements, it is possible to determine the fetal requirement during pregnancy by analyzing the chemical component of the fetus at each lunar month.The author attempted the analysis of chemical components on 24 fetuses varying from the third gestation month to the mature newborn and followed up the requirements of N, Ca and P in accordance with the gestation month.In the meantime the quantitative relationships of N, Ca and P were observed on the fetus which was divided into the skin, supportive, and soft tissues, and on the fetal attachments.The results of the experiment were summarized as follows;1) The average amounts of N, Ca and P for the Japanese mature newsborn were 18, 7.24 and 3.81g/kg, respectively.2) The accumulation of N. Ca and P in fetus is notable at the third trimester, especially during the last two months of pregnancy. The average daily amount of these elements accumulated in fetus raises as the pregnancy advances.3) 55% of N, 60% of Ca, and 57% of P, were accumulated in the fetus during the last two months of pregnancy.4) 96-98% of Ca, 87-75% of P in the fetus were contained within the supportive tissues, and the amount of Ca in the fetal attachments was only 1.5% of that in the fetus.5) The ratio of Ca to P in the supportive tissues of fetus from the fifth month to mature newborn show its peak at the eighth month and remained almost constant thereafter.