The literature of normal pregnancy affords, so far as we are aware, no series of observations on the basal metabolism beginning with early pregnancy and continuing through the puerperium. Magnus-Levy,1 in 1904, and Hasselbach,2 in 1912, each reported a single case observed before conception and during pregnancy. Leo Zuntz,3 in 1910, reported two cases with observations beginning in the fourth to the sixth months and continuing to delivery, and a third case in which observations were made in the sixth month only.
Magnus-Levy found both an absolute and relative increase in the oxygen consumption per unit of weight as early as the third month of pregnancy. Zuntz and other observers, however, found no increase in the oxygen consumption per kilogram, or, if any occurred, it appeared only late in the gestation period. Carpenter and Murlin,4 in 1911, showed that the curve of total energy production of mother and child suffered
ROOT HF, ROOT HK. THE BASAL METABOLISM DURING PREGNANCY AND THE PUERPERIUM. Arch Intern Med (Chic). 1923;32(3):411-424. doi:10.1001/archinte.1923.00110210100009