The importance of low blood urea nitrogen levels in pregnant patients undergoing hemodialysis to optimize birth weight and gestational age.

Most published reports indicate that intensified hemodialysis results in better pregnancy outcomes. Here we studied clinical characteristics and the outcomes of 28 pregnant women receiving hemodialysis. We found an association between maternal blood data and birth weight, and gestational age and outcomes. There were 18 surviving infants who were followed up for one year. In the others there were 4 spontaneous abortions, 1 stillbirth, 3 neonatal deaths and 2 deaths after birth. Analysis of blood chemistry for 20 pregnancies from 12 weeks of gestation until delivery showed that the average hemoglobin level was significantly higher in the group that successfully delivered than in the unsuccessful group. There were significant negative relationships between the blood urea nitrogen (BUN) level and the birth weight or gestational age in the latter cohort. A birth weight equal to or greater than 1500 g or a gestational age equal to or exceeding 32 weeks corresponded to BUN levels of 48-49 mg/dl or less. Whether the low BUN is the direct cause of the improved outcome remains to be examined.