Serum calcium and blood loss at delivery

The purpose of the study was to investigate the relationship between predelivery serum calcium values and blood loss at delivery as reflected by changed in selected hematologic values from predelivery to second postpartum day. Twenty-nine women who delivered at the Shiprock Indian Health Service Hospital and 25 women who delivered at Hill Air Force Base Hospital were studied. Each subject had a total serum calcium level determined prior to delivery. Hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were measured for each subject prior to delivery and again on the second postpartum day. Changes in these hematologic values were interpreted as indices of blood loss at delivery. Pearson product-moment correlations were calculated to test the hypothesized relationship between serum calcium and changes in the hematologic values. No statistically significant correlations were observed. Previously reported association of blood loss with maternal age, parity, length or labor, and infant weight are supported by this study. Although norms do no exist for drops in hematocrit and hemoglobin per volume of blood loss for parturient women, the magnitude and frequency of drops in these values observed in this study speaks to the excessive loss of blood by women who participated in the study. Contrary to the expectation of the investigator, the Navajo women form Shiprock did not have serum calcium levels lower than the primarily Caucasian sample for Hill; neither did the Navajo subjects lose more blood at delivery than the subject from Hill. Initially, it was assumed that the Navajo tendency to lower serum calcium levels and greater blood loss at delivery were related to racial differences. Observation of the same tendencies among the subjects from Hill suggest that these trends to lower serum calcium and excessive blood loss at delivery are a function of the interaction of other variables, perhaps socioeconomic or nutritional status.