METABOLISM OF WOMEN DURING THE REPRODUCTIVE CYCLE

A case study extending over an 8-year period of child-bearing and child-rearing has been made on a woman when she and her children were known to enjoy buoyant health. Uninterrupted nitrogen metabolic responses during the last half of fetal development and the physiological preparation of the maternal body for lactation and the extension of these observations into parturition, puerperium and 8 weeks of lactation showed where some of the stresses and strains of maternity lay. The results confirm previous considerations derived from intermittent balances in two former reproductive cycles in the same woman. During the last 145 days in gestation there was an average net storage of 3.1 gm. and a maternal retention of 2.6 gm. of nitrogen daily resulting in a total observed accumulation of 446 gm. at term. On the day of delivery the chemically determined maternal loss in blood, placenta, amniotic fluid and vomitus amounted to 46.0, 20.1, 0.08, 0.24 gm. of nitrogen, respectively; the total loss from the body beyond the food consumed amounted to 54.6 gm. of nitrogen in addition to that contained in the fetus. The nine daily balances during the lying-in period showed an average daily loss of 5 gm. of nitrogen. From the tenth to the fifty-third day of lactation there was an average daily loss of 0.87 gm. of nitrogen. By the fifty-third day of milk flow the gestatory reserve nitrogen had been reduced by delivery, puerperium and lactation losses of 54.6, 44.6 and 38.3, respectively leaving a total of 310 gm. of nitrogen stored only in the last half of pregnancy. When the approximate fetal content of 58.6 gm. of nitrogen is deducted from the final maternal reserve, the accountable losses of the reproductive cycle by the fifty-third day of lactation had left a maternal reserve of 250 gm. of nitrogen for future dissipation or enrichment of the maternal body at termination of the reproductive cycle.