We in investigated the impact of maternal and fetal variables on cord blood (CB) haemopoietic stem/progenitor cell content. These included maternal age, ethnic origin, parity, ABO and Rhesus D blood group, antenatal haemoglobin, alcohol and cigarette consumption at time of registration, mode of delivery, duration of the first and second stages of labour, gestational age, birth weight, cord pH and cord erythrocyte mean cell volume (MCV). Cord volumes and total nucleated cellularities (TNC) were recorded, the colony assay for granulocyte-macrophage colony-forming-cells (CFU-GM) was used to quantify the progenitor cells and the potential of CFU-GM to produce secondary colonies on replating was used as a measure of progenitor cell quality. We found: (1) significantly greater (P = 0.04) volumes were collected from babies who weighed greater than or equal to 2.5 kg Versus babies with a birth weight <2.5 kg; (2) significantly greater numbers of mononuclear cells (MNC) from mothers who drank 0-3 units versus those who drank greater than or equal to 4 units of alcohol weekly (P = 0.03), and in babies with a cord pH less than or equal to 7.1 v > 7.1 (P = 0.02); (3) Significantly greater numbers of cord CFU-GM in mothers who drank 0-3 v greater than or equal to 4 units weekly (P=0.004) and smokers of greater than or equal to 10 v 0-9 cigarettes daily (P=0.02) and in spontaneous vaginal deliveries than assisted vaginal and caesarean deliveries (P=0.04), and (4) the potential of CFU-GM to produce secondary colonies was significantly greater in CB derived from Caucasians than from non-Caucasians (P=0.02); in assisted vaginal delivery v spontaneous vaginal (P=0.02) and in deliveries with prolonged first stage of labour v short first stage of labour (P=0.04). We conclude that antenatal and perinatal variables may influence the CB stem/ progenitor cell yield available for transplantation.