the data of "Differences of the Neutrophil-Lymphocyte Ratios at 24 hours Postpartum Women Between two Delivery Modes and their Relationship to the Onset of Lactation: a Prospective Cohort Study"

Background: Delayed onset of lactation is a key factor for the low rate of exclusive breast-feeding during the 6 months after cesarean section. The mechanism of delayed onset of lactation is not clear. Milk production depends largely on mitochondria adenosine triphosphate (ATP) synthesis, and neutrophil-lymphocyte ratio is closely related to mitochondrial DNA copy number and ATP production. At present, it has not been explored whether a difference in neutrophil-lymphocyte ratio exists between the vaginal delivery group and the cesarean delivery group and, if so, whether the difference correlates to the time of onset of lactation. Objectives: To identify whether neutrophil-lymphocyte ratio at 24 hours after delivery is different between mothers in the cesarean section and the vaginal birth and whether the neutrophil-lymphocyte ratio is related to delayed onset of lactation. Design: The study adopted a prospective cohort study design. Settings: Maternity units of an Obstetrics & Gynecology Hospital. Methods: Mother-infant pairs were entered the vaginal birth group and the cesarean section group according to the way they gave birth. The neutrophil-lymphocyte ratio was calculated as the absolute value of neutrophils divided by the absolute value of lymphocytes based on full blood counts. Before delivery, the full blood counts were obtained from medical records. While after delivery, the blood samples were drawn at the time of 24 hours postpartum and then blood cells are classified and counted. The onset of lactation was confirmed by the maternal perception of breast fullness. The neutrophil-lymphocyte ratio and its relationship with the onset of lactation were analyzed by multivariable regression. Results: The neutrophil-lymphocyte ratios of the two groups were both elevated after deliveries. Based on the covariance analysis, after adjusting the baseline in full blood counts before delivery, the neutrophil-lymphocyte ratio in the cesarean group is higher than the ratio in the vaginal group after delivery (p =.000). Also, after adjustment of confounding factors, the multivariable regression analyses showed that increased neutrophil-lymphocyte ratio was correlated with delayed onset of lactation (95% CI 0.285-1.646). Conclusions: Compared with the vaginal delivery, Neutrophil-lymphocyte ratio in the cesarean section is higher and is related to a delayed onset of lactation. The mechanism for this delay onset of lactation may be due to the decreased mitochondrial DNA copy number and ATP production