To clarify postnatal needs for retinol, we have measured the retinol concentration in paired samples of umbilical and umbilical artery blood immediately after uncomplicated term delivery (n=8). In these 8 infants, umbilical vein concentration was always higher than umbilical artery. As shown in the figure, concentration gradients varied widely from baby to baby, but, for each cord pair, there was a significant correlation of gradient with concentration of retinol in the umbilical vein. Tissue uptake of retinol was estimated assuming a 100 ml/kg/minute umbilical blood flow, a HCT of 50% and non participation of RBC in tissue uptake. It varied from 0.58 to 8.42 mg/kg/day (mean of 3.36)*. This represents a higher supply of retinol than that provided by routine postnatal nutrition. In another group of 8 term infants cord retinol levels were compared to capillary blood levels at age 11 to 24 hours. A mean decrement of 28% in retinol concentration in paired samples was found (8.1μg/dl ± 6.7 SD, range 0 to 20). Conclusions: This preliminary data suggests that optimal retinal intake after birth for growing preterm and term infants has probably been underestimated.

figure 1

Figure 1