Consistency comparison: Comparing the ΔCq standard deviations of paired serum and plasma samples across the three study time points, analysing four stably expressed miRNAs; hsa-miR-222-3p, hsa-miR-23a, hsa-miR-30e-5p and hsa-miR-451a. *P<0.05. miRNA/miR, microRNA; 1, second trimester of pregnancy (18-24 weeks); 2, weeks 36-40 of the third trimester; 3, 6 weeks post-partum.