BackgroundAccurate prediction of parturition is paramount to ensuring monitoring of delivery and preventing complications. Assessing the pH and electrolytes of the mammary gland secretions (MGS) helps detect impending parturition. As conductivity is related to electrolyte concentrations and pH, it could be a useful alternative for predicting impending parturition; however, this hypothesis warrants a critical assessment.ObjectivesTo assess the ability of conductivity, pH, and Brix in the MGS to predict parturition and to investigate their associations.Study designField study.MethodsThe MGS of periparturient mares (n = 241) was assessed daily for conductivity, pH, and Brix index from 320d until parturition. Receiving operating curve cut‐off values for conductivity (≤4.8 mS/cm), pH (≤6.4), and Brix index (>23.6%) were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for predicting parturition in ≤24 h.ResultsImpending parturition was associated with a reduction in conductivity and pH (p < 0.05), and conductivity was strongly correlated with pH (r = 0.88) and Brix (r = −0.80) (p < 0.05). Sensitivity, specificity, PPV, and NPV for parturition in ≤24 h for conductivity (82%, 91%, 77%, and 92%, respectively), pH (79%, 84%, 81%, and 71%, respectively), and Brix (72%, 79%, 66%, and 83%, respectively) were determined separated and pairwise. Of interest, the sensitivity, specificity, PPV, and NPV, of combining conductivity and pH, were 80%, 95%, 90%, and 88%, respectively. Conductivity (≤4.8 mS/cm) presented the greatest odds ratio for predicting parturition in ≤24 h, and coupling it with pH (≤6.4 pH units) doubled its odds ratio (i.e., 25.4–62.3).Main limitationsField study.ConclusionThe conductivity of MGS is a sensitive and specific method to predict parturition. This is the first large‐scale study showing that a combination of conductivity and pH is useful for predicting parturition in mares. The methods employed can likely apply to other settings with similar results.

中文翻译：

---

乳腺分泌物的电导率是母马分娩的敏感且特异的预测因子

背景准确预测分娩对于确保分娩监测和预防并发症至关重要。评估乳腺分泌物 (MGS) 的 pH 值和电解质有助于检测即将分娩。由于电导率与电解质浓度和 pH 值相关，因此它可能是预测临产的有用替代方案；目的评估 MGS 中的电导率、pH 值和白利糖度预测分娩并调查其关联的能力。研究设计实地研究。方法围产期母马的 MGS（n= 241) 从 320 天到分娩，每天评估电导率、pH 值和白利糖度指数。使用电导率 (≤4.8 mS/cm)、pH (≤6.4) 和白利糖度指数 (>23.6%) 的接收操作曲线截止值来计算灵敏度、特异性、阳性预测值 (PPV) 和阴性预测值(NPV) 用于预测 ≤24 小时内的分娩。结果临产与电导率和 pH 值的降低相关（p< 0.05），电导率与 pH 值密切相关（r= 0.88) 和白利糖度 (r= -0.80) (p< 0.05）。≤24 小时内分娩的电导率（分别为 82%、91%、77% 和 92%）、pH（分别为 79%、84%、81% 和 71%）的灵敏度、特异性、PPV 和 NPV 、和白利糖度（分别为 72%、79%、66% 和 83%）分别成对测定。有趣的是，电导率和 pH 值组合的灵敏度、特异性、PPV 和 NPV 分别为 80%、95%、90% 和 88%。电导率 (≤4.8 mS/cm) 是预测 ≤24 小时内分娩的最大优势比，将其与 pH（≤6.4 pH 单位）耦合使其优势比翻倍（即 25.4–62.3）。主要局限性现场研究。结论电导率MGS 是预测分娩的敏感且特异的方法。这是第一项大规模研究表明电导率和 pH 值的结合可用于预测母马的分娩。所采用的方法可能适用于具有类似结果的其他设置。