Department of Social Research, University of Turku, Turku, Finland.
Department of Clinical Medicine, Turku Brain and Mind Center, FinnBrain Birth Cohort Study, University of Turku, Turku, Finland.
Am J Hum Biol. 2021 Nov;33(6):e23561. doi: 10.1002/ajhb.23561. Epub 2021 Jan 4.
Glucocorticoids are one component of human milk (HM) potentially affecting offspring development. Previous studies have identified various maternal, obstetric and socioeconomic characteristics that are associated with HM cortisol concentration but the literature is still scarce concerning these determinants in human populations. We aimed to identify which factors are linked with HM cortisol concentration at 2 months postpartum.
We analyzed data from 340 lactating Finnish mothers using ordinary least squares regression with log-transformed HM cortisol concentration as the dependent variable. Potential predictors included obstetric and maternal factors (maternal age, parity status, delivery mode, gestational age, pre-pregnancy obesity, and smoking in pregnancy), socioeconomic status (education and socioeconomic class), subjective economic well-being, maternal psychosocial factors (postpartum depression and anxiety symptoms), infant sex and age, and HM sample characteristics (time of the day and season of the year at sample collection).
The strongest and most robust predictors were season of the year of sample collection and parity status. HM cortisol concentration was significantly higher for primiparas than multiparas. HM samples collected in summer showed significantly higher cortisol concentrations than those collected in winter, spring or autumn.
The findings suggest that parity and season of the year at sample collection may be important factors to control for when examining HM cortisol. The strongest and most robust associations were related to maternal and sample characteristics and not to socioeconomic and psychosocial distress. This may be related to the fact that the study was conducted in a low-risk population.
皮质醇是人乳（HM）的一个组成部分，可能会影响后代的发育。先前的研究已经确定了各种与 HM 皮质醇浓度相关的母体、产科和社会经济特征，但关于这些决定因素在人类中的研究仍然很少。我们旨在确定哪些因素与产后 2 个月的 HM 皮质醇浓度有关。
我们使用普通最小二乘法回归分析了 340 名芬兰哺乳期母亲的数据，将 HM 皮质醇浓度的对数转换作为因变量。潜在的预测因素包括产科和母体因素（母亲年龄、产次、分娩方式、胎龄、孕前肥胖和孕期吸烟）、社会经济地位（教育和社会经济阶层）、主观经济幸福感、母体心理社会因素（产后抑郁和焦虑症状）、婴儿性别和年龄以及 HM 样本特征（采集样本的时间和季节）。
最强和最稳健的预测因素是样本采集的季节和产次。初产妇的 HM 皮质醇浓度明显高于多产妇。夏季采集的 HM 样本的皮质醇浓度明显高于冬季、春季或秋季采集的样本。
这些发现表明，在检查 HM 皮质醇时，产次和样本采集的季节可能是需要控制的重要因素。最强和最稳健的关联与母体和样本特征有关，而与社会经济和心理社会压力无关。这可能与研究在低风险人群中进行有关。
