In this study, we analyzed the obstetric factors affecting total nucleated cells (TNC) content of cord blood units to establish the criteria for umbilical cord blood (UCB) donor selection in our geographic area.UCB was collected from normal uncomplicated pregnancies. In every case, following data were recorded: (1) gestation length; (2) type of delivery (cesarean or vaginal); and (3) newborn characteristics: weight and sex. For each sample, TNC content, percentage and number of CD34+ cells, and viability were analyzed.The results showed that TNC content increases with cord blood volume, gestational length and newborn weight. The mean blood volume and the mean TNC per unit were 42.37 ± 13.5 ml and 55.49 ± 19.4 × 107, respectively. Stepwise regression analysis revealed a positive and significant correlation (r= 0.89) between these two variables. Meanwhile the CD34+ cell content remains unchanged in deliveries at 32–40 weeks of gestation. The mean CD34+ percentage obtained was 0.37 ± 0.06, and the total number of CD34+ cells was 4.827 ± 0.8204 × 104 / mL UCB.Concluding, the maternal and obstetric factors have a significant impact on UCB cell quantity and quality. The main criteria for UCB collection and storage resulted to be: a gestational age higher than 36–40 weeks and newborn weight > 3200g; gestation number ≤ 2 and placental weight > 700g can be added to the standard criteria to improve the bank efficiency. Our results have also become helpful in evaluating stored UCB units to establish the adequacy for clinical transplant utilization.