Umbilical cord blood (UCB) has been widely used as an alternative to haematopoietic stem cell (HSC) in transplantation for both malignant and non-malignant diseases including metabolic diseases. Approximately 30,000 transplantations using UCB, either from a family-related donor or non-related donor, have been reported worldwide [
1]. This may be due to the ability of the HSC pool within UCB to proliferate and differentiate more rapidly, being superior to HSC extracted from bone marrow and peripheral blood [
2,
3]. Additionally, it is easier to collect UCB since it poses less risk to the donor (pregnant mother), has less risk of infection, is accessible, and most importantly the loose criteria for Human Leucocyte Antigen typing match with less graft versus host disease [
4]. However, the success rate of HSC transplant depends on the number and engraftment of infused nucleated cell count (NCC) and CD34+ cells [
4‐
6]. For a standard transplant procedure, approximately 1–3 × 10
7 cell per kg of recipient weight is needed, whereby a higher dose of infused NCC and CD34+ cells will result in a shorter period of engraftment [
5]. Colony forming unit (CFU) assay is extensively used as a medium to study the capability of HSC to proliferate and differentiate by their ability to form progenitor colonies in methylcellulose semisolid media [
7]. In transplantation, CFU assay is a better predictor of haematopoietic engraftment [
8] and an important parameter when selecting the unit of UCB for transplantation [
9]. Thus, most UCB banks have a fixed policy in selecting good quality UCB for banking based on adequate NCC and CD34+ cell counts including the ability of these cells to proliferate and differentiate [
10].
Studies have reported that several obstetric factors such as maternal age, gestational age, maternal blood pressure, delivery time, route of delivery, and method of UCB collection affected the number and quality of the HSC pool within UCB [
11‐
13]. A shorter period of UCB collection from the umbilical cord including HSC processing will give a higher number of CD34+ cells [
11]. Several neonatal factors such as gender and weight also influenced the number of HSC. A heavy baby will give a high number of NCC, CD34+ cells and CFU granulocyte-monocyte [
14]. The gender of the baby also produces different cell ratios with a male baby giving a higher CD34+ cells but lower NCC and CFU-granulocyte monocyte [
10] while a female baby with a longer pregnancy period will give higher NCC [
11]. However, not many studies reported on the quality and potency of HSC from UCB related to the above mentioned obstetric and neonatal factors in a diseased pregnancy such as in gestational diabetes mellitus (GDM) and preeclampsia. Both GDM and preeclampsia are common diseases in pregnant mothers especially for those who already have a history of diabetes and hypertension in a previous pregnancy. Stallmach et al. (1998) reported reduced endothelial cells including low hepatic haematopoiesis in the foetus, which could compromise the quality and potency of progenitor cells in UCB [
15]. CD34+ cell count has also been reported to be significantly lower in patients with GDM compared to patients with hypertension and control (normal pregnancy) [
16]. In this study, the quality and potency of NCC, CD34+ cells, and endothelial progenitor cells from HSC UCB will be further investigated in pregnant mothers with preeclampsia. In addition, the correlation between obstetric and neonatal factors with the quality of HSC will also be analysed. We hypothesised that preeclampsia will affect the quality and potency of HSC from UCB. These findings will be useful in guiding pregnant mothers with preeclampsia in considering future UCB banking.