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.

研究背景：延迟泌乳启动是剖宫产术后6个月内纯母乳喂养率偏低的关键影响因素。目前延迟泌乳启动的具体机制尚未明确。乳汁生成在很大程度上依赖于线粒体三磷酸腺苷（ATP）合成，而中性粒细胞-淋巴细胞比值（neutrophil-lymphocyte ratio）与线粒体DNA拷贝数及ATP生成密切相关。目前尚未明确剖宫产组与阴道分娩组的中性粒细胞-淋巴细胞比值是否存在差异，若存在差异，该差异是否与泌乳启动时间相关。
研究目的：明确分娩后24小时的中性粒细胞-淋巴细胞比值在剖宫产产妇与阴道分娩产妇间是否存在差异，以及该比值是否与延迟泌乳启动相关。
研究设计：本研究采用前瞻性队列研究设计。
研究场景：某妇产医院产科病房。
研究方法：按照分娩方式将母婴对分为阴道分娩组与剖宫产组。基于全血细胞计数（full blood counts）结果，以中性粒细胞绝对值与淋巴细胞绝对值的比值计算中性粒细胞-淋巴细胞比值。分娩前的全血细胞计数数据来源于病历记录；分娩后于产后24小时采集血液样本，进行血细胞分类计数。通过产妇主观感知的乳房充盈情况确认泌乳启动时间。采用多变量回归（multivariable regression）分析中性粒细胞-淋巴细胞比值及其与泌乳启动时间的相关性。
研究结果：两组产妇分娩后的中性粒细胞-淋巴细胞比值均升高。经协方差分析校正分娩前全血细胞计数基线水平后，剖宫产组产后的中性粒细胞-淋巴细胞比值高于阴道分娩组（p=0.000）。此外，在校正混杂因素后，多变量回归分析显示，中性粒细胞-淋巴细胞比值升高与延迟泌乳启动存在相关性（95%置信区间：0.285-1.646）。
研究结论：与阴道分娩相比，剖宫产产妇的中性粒细胞-淋巴细胞比值更高，且该比值与延迟泌乳启动相关。延迟泌乳启动的潜在机制可能与线粒体DNA拷贝数降低及ATP生成减少有关。