This is a prospective longitudinal study done at the clinical pathology division of department of Pathology and Central Laboratory Services, Sri Ramachandra Medical College & Research Institute, Chennai, South India. This study was approved by the Institutional Ethics Committee, and the participants are 120 randomly selected new babies born to women at Sri Ramachandra Medical College, Hospital. Mothers gave their consent and were of 21-35 years of age having uneventful pregnancy with haemoglobin above 10g/dl and vaginal delivery of a single baby. Mothers with multiple pregnancies (more than 2), eclampsia and preeclampsia, diabetes mellitus, cardiovascular, respiratory, nervous, genitourinary diseases were excluded. The new borns were full term at birth (37-42 weeks), with normal birth weight (2.5-4kg) and normal APGAR score. They were free of congenital anomalies prenatally by ultrasound and by physical and systemic examination at birth.

As soon the umbilical cord was clamped and cut by the obstetrician, 3 ml of cord blood was collected in a pre labeled EDTA vaccutainer by milking. It was transported to lab immediately and processed within 3 hours of collection. Processing for complete blood count was done in Beckman Coulter LH780. Peripheral smears were examined to verify the results.

The results were entered in Microsoft excel and analyzed with SPSS statistics 16 software. The mean and SD for various parameters were calculated.

Comparison of results according to sex were done. Biological reference interval for various hematologic parameters were established and compared with literature. The mean and SD values of CBC in the UCB of males and female neonates (ratio 1:1.05) are shown in [Table/Fig-1]. There was no statistically significant difference (p>0.05) between the results for each parameter. The results of RBC parameters of the present study with comparison of literature reports is shown in [Table/Fig-2] and WBC and platelet parameters in [Table/Fig-3].

The biological reference interval for Hb, RBC count WBC count, polymorph count and platelets counts, hematocrit, WBC count, polymorph count and platelet counts were lower in a study conducted at Greece than the present study. The Red cell distribution (RDW) was higher and Nucleated red blood cells (NRBC) count was lower in a study from Iraq when compared with ours. A study from Chandigarh, India showed a higher hemoglobin value than our result. A study from Nigeria showed low MCHC, and high RDW than ours.

The cellular components of UCB include stem cells which include mesenchymal stem cells, hematopoietic stem cells and multipotent non-hematopoietic stem cells and mature cells of hematopoietic stem cells namely RBC, WBC and platelets [2]. UCB is a source of hematopoietic stem cell transplant for various malignant and non-malignant hematologic conditions. Though the component of mesenchymal stem cells is low in number due to their high proliferation rate, cord blood can be considered as a source of mesenchymal stem cells also. Moreover, studies have indicated that cord blood reflects fetal hematopoietic and health status of new born and it can be considered an ideal source for laboratory analysis instead of new born blood, the collection of which is difficult. The disease status of new born like asphyxia, meconium staining and chorio amminonitis are reflected in UCB [3,4]. Also maternal conditions like smoking, anaemia, diabetes, preeclampsia and mode of delivery which influence the health status of new born are reflected in the UCB [5–9]. Hemogram of an individual varies according to age, sex, race and geography. The same may be true with umbilical cord hemogram also. Hence, its need of the hour to establish biological reference interval before studying the influence of maternal and new born conditions. Though it dates back in 1924 Lippman did blood count analysis on UCB, studies on this aspect were few in health and diseased condition. A study done in Chandigarh, India in 1992, did not include RBC indices. The present study is the first of its kind with analysis of all the parameters.

In the present study, no significant difference was found between the values of males and females. Adewumi et al., also found no difference when they analyzed cord blood of Nigerian neonates [10]. But a study from Greece showed statistically significant difference in RDW, WBC count, neutrophil count and platelet count and a study done in Iraq showed difference in neutrophils percentage alone [11,12]. However, both the studies showed lower neutrophil percentage in males when compared to females.

The study conducted in Greece showed lower value of Hb, RBC count, HCT, WBC count, polymorph count and platelet count when compared with the present study [11]. This may be due to dilution of cell components when blood is collected in UCB bags in their study. The RDW was higher and the NRBC were lower in a study done at Iraq when compared to the present study. However, the blood was collected from umbilical vein alone [12]. A study from Nigeria showed low MCHC and high RDW while another study showed a comparable MCHC [10,13]. Indian study from Chandigarh was comparable to the present study except for Hb and lymphocyte percentage which were found to be higher. However, the study was done manually [14]. When compared with Indian text book reference range at birth, the present study was comparable while the Hb value and RBC counts are lower than western text book reference range [15,16]. Umbilical cord blood is stored after screening which involves high cost. This can be avoided and blood can be rejected if the hematological parameters are out of range to improve outcome of UCB stem cell transplant. Also the neonate can be monitored carefully for disease state if the UCB parameters are found to be out of range.

The biological reference interval established is a useful guide to neonatologists, UCB stem cell transplant hematologist and also for future UCB analysis in health and disease. The biological reference interval needs to be established at every region in this era of stem cell research.