The effects of cord clamping time on lymphocyte subgroups in late preterm and term infants

Aim: To evaluate the effect of cord clamping time on lymphocyte subgroups in late preterm and term infants Materials and Methods: The study was conducted between February 2016 - March 2016 at Çukurova University Faculty of Medicine. Seventy-four infants between 34 and 41 weeks of gestation were included in the study. Of these, 37 were clamped immediately after the baby was out of the uterus and the remaining 37 were clamped after waiting one minute at the uterus level or below 30 cm. Babies were divided into two groups as term and preterm. Prenatal, natal, postnatal characteristics of the infants were recorded. Biochemical, haematological and lymphocyte subgroups were investigated in cord blood and venous blood at day 7. Lymphocyte subgroups were evaluated by flow cytometry. Results: There was no change in hemoglobin and hematocrit values with delayed cord clamping time neither in the cord blood nor in the 7th day peripheral venous blood (p> 0.05). With the delay of cord clamping, the percentage of CD3+ T lymphocytes in cord blood of preterm infants decreased and this decrease continued at day 7 (p = 0.01, p = 0.013). On the contrary the CD19+ B lymphocyte levels in the cord blood of preterm infants increased and this increase also continued at day 7 (p = 0.002, p = 0.043). There was no difference in CD4+ T lymphocyte percentages observed in cord blood of preterm infants, though a decrease was detected on day 7 (p> 0.05, p = 0.007). Hospitalization rates and need for mechanical ventilation were significantly lower in the delayed cord clamping preterm infants group (p = 0.02, p = 0.04). The percentages of CD8+ T lymphocytes in cord blood were higher in preterm infants with sepsis than those without (p = 0.04). In infants with immediate cord clamping, the percentage of CD3+ T lymphocytes in the cord blood was decreased as the gestational week increased, and this decrease persisted on day 7 (p = 0.03, R²=0.25, p = 0.017, R²=0.02). The percentage of CD8+ T lymphocytes in the cord blood was decreased as the gestational week increased in infants with immediate cord clamping but this decrease was not detected in peripheral venous blood collected on day 7 (p = 0.02, R²=0.161, p> 0.05, R=0.23). In infants with immediate cord clamping, CD19+ B lymphocyte counts in cord blood were found to increase as gestational week increased, but this increase was not detected on day 7 (p = 0.004, R²=0.23, p = 0.63, R=0.15). Conclusion: The delay of cord clamping time in term and preterm infants seems to have no impact on the rate of sepsis development and phototherapy requirement. The rate of hospitalization and the need for mechanical ventilation were found to be lower in infants whose cord clamping time was delayed. Larger series of studies are needed to assess the effect of decrease in CD3+ T lymphocyte percentages and the increase in CD19+ B lymphocyte percentages on the development of infection in late preterm infants who have delayed cord clamping. Keywords: Late preterm, Term, Cord clamping time, Lymphocyte subgroup, Sepsis.