The vitamin E-binding protein afamin increases in maternal serum during pregnancy

AbstractBackgroundAfamin is a liver-derived plasma glycoprotein with vitamin E-binding properties and a putative function in fertility. This study evaluated serum afamin concentrations during and postpartum to uncomplicated pregnancies and investigated a potential association between afamin concentrations and pregnancy outcome.MethodsAfamin serum concentrations were measured in women with uncomplicated pregnancies in a retrospective cohort (n=466) at different gestational ages and a prospective observational study (n=76) in the first, second and third trimester. Furthermore, afamin was determined in the first trimester in a cross-sectional pilot study including women with preeclampsia (PE), pregnancy-induced hypertension (PIH) and women without pregnancy complications (n=13 each). Finally, expression of afamin was investigated in human placental tissue by RT-PCR and immunohistochemistry.ResultsAfamin concentrations increased linearly almost two-fold during pregnancy in both retrospective and prospective studies in women without pregnancy complications with median afamin serum concentrations of 61.9mg/l, 79.6mg/l, and 98.6mg/l in the first, second, and third trimester, respectively. After delivery, median afamin concentrations decreased to baseline values of 54.6mg/l. In the pilot study with pregnancy complications, women with PE displayed significantly higher median afamin concentrations than did women with uncomplicated pregnancy (70.0mg/l vs. 55.4mg/l, P=0.007). Expression analyses revealed no placental afamin expression at either mRNA or protein level in uncomplicated pregnancy.ConclusionA linear increase in the maternally expressed glycoprotein afamin during pregnancy may serve as basic reference for subsequent investigations of afamin in pregnancy-related disorders