Maternal serum midkine level in fetal growth restriction: a case-control study.

Objectives: To compare maternal serum midkine (MK) level in pregnant women with idiopathic fetal growth restriction (FGR) and healthy. In addition, we assessed the value of maternal serum MK level in predicting neonatal intensive care unit (NICU) admission.

Methods: A total of 144 pregnant women were included, 72 with idiopathic FGR and 72 healthy in this study. The control group was matched for the mother's age, parity, gestational age, and pre-pregnancy body mass index (BMI) with the idiopathic FGR group at the time of recruitment into the study and sample collection.

Results: Serum MK level is higher in the idiopathic FGR than the control group (0.24 ng/mL (0.19-0.32) vs. 0.18 ng/mL (0.14-0.23), p<0.001). In addition, we compared the maternal serum MK level of those with and without NICU admission in the FGR group (0.25 ng/mL (0.19-0.37) vs. 0.21 ng/mL (0.18-0.28), p=0.014). We performed ROC curve analysis to serum MK level predicting NICU admission in the FGR group (AUC: 0.668, %95 CI [0.550, 0.785], p=0.014). A sensitivity of 63% and a specificity of 62% for the serum MK level were achieved with a cut-off value of 0.22 for NICU admission.

Conclusions: To the best of our knowledge, this study is the first to compare maternal serum MK level in pregnant women with idiopathic FGR and healthy. We showed that maternal serum MK level was significantly elevated in pregnant women with FGR than healthy.