Association of blood loss during delivery to B-hemoglobin

To study the association between blood loss during delivery and B-hemoglobin before and after delivery (3 days and 10 weeks, respectively).

Information on blood loss for 693 women, 93.9% of all parturients during the study period, was extracted from the original medical records. B-hemoglobin was analyzed at the antenatal maternal health care unit at the last visit before delivery, in capillary samples taken on the ward on the 3rd day, or 10 weeks after delivery. Associations were estimated with Pearson's parametric correlation coefficient.

Altogether, 31.3% of all parturients had a higher B-hemoglobin value on the 3rd day after delivery than on the last visit to the maternal health care unit before delivery; the mean intrapartum blood loss was 375 ml (range 100-2,200 ml). The correlation coefficient between B-hemoglobin on the 3rd day after delivery and blood loss was r = -0.53. When the last value recorded at the antenatal maternal health care unit was included in the analysis, the correlation coefficient remained virtually unchanged (r = -0.52). Only 14 (blood loss < or = 600 ml), or 11% (blood loss >600 ml) of the variation in the B-hemoglobin was accounted for by the amount of blood loss. No significant correlation coefficient was evident for B-hemoglobin 10 weeks after delivery vis-à-vis blood loss, irrespective of whether iron supplementation was administered (r = 0.01) or not (r = 0.17).

The weak association between intrapartum blood loss and B-hemoglobin suggests that the value of B-hemoglobin determined after delivery may be less indicative than previously thought. This conclusion is strengthened by the fact that only a minor part (< or = 14%) of the variation in B-hemoglobin on the 3rd day after delivery is explained by the amount of blood lost.