The Mediation Effect Of Glucocorticoids In Cord Blood For The Association Between Gestational Blood Glucose And Birth Weight

Background: Gestational diabetes mellitus is a common gestational complication and can increase birth weight,but the mechanism is not is still unknown.Glucocorticoids are important hormones that regulate the physiological functions.Studies have shown that gestational glucocorticoid levels are inversely related to birth weight.Meanwhile,blood glucose levels during pregnancy are closely related to the levels of glucocorticoids in pregnant women and fetuses.However,there is no report that explore the association of glucocorticoids,blood glucose levels and birth weight and the mediation of glucocorticoids.Objective:(1)To explore the associations between gestational blood glucose levels,glucocorticoids in umbilical cord blood and birth weight.(2)To investigate whether glucocorticoids are the mediators between higher maternal blood glucose levels and larger birth weight.Methods: The total population including 1,712 mother-newborn pairs was from the prospective birth cohort established between October 2013 and May 2015.The basic information of participants was collected through the questionnaire,other maternal inspection information such as maternal gestational diabetes,OGTT test results,etc.were collected through the medical records.Umbilical cord blood was collected during delivery.Levels of three glucocorticoids(cortisol,Cortisone,11-deoxycortisol)determined using LC-MS/MS.Linear regression and logistic regression models were used to analyze the association among gestational diabetes mellitus and blood glucose levels,umbilical glucocorticoid levels,and birth weight.Finally,the mediation model is used to explore the effect of glucocorticoids between blood glucose and birth weight.Results:(1)The birth weight increased with the elevating gestational blood glucose levels,among which the fasting blood glucose was the most significant variation.For every one unit increase in fasting blood glucose,birth weight increased by 91.12g(95%CI:53.24,129.01).Additionally,elevated blood glucose levels increase the risk of macrosomia and LGA.(2)Low levels of glucocorticoids in umbilical cord blood lead to birth weight increasing.For every unit of cortisol reduction,birth weight increased 29.17g(95%CI:-42.69,-15.65).(3)There was a significant negative correlation between blood glucose levels during pregnancy and glucocorticoid levels in cord blood.(4)The results of the mediation model showed that cortisol was a mediated variable in gestational blood glucose increasing birth weight.In the correlation between fasting blood glucose,1h plasma blood glucose and 2h plasma blood glucose levels and birth weight,the indirect effects of cortisol in the total effects were 4.25%(0.30%,12.32%),8.62%(1.18%,37.19%),6.85%(0.72%,21.99%)respectively.Conclusion: Glucocorticoids can mediate the association between higher gestational blood glucose and larger birth weight.