Abstract: Objective To analyze the expression levels and clinical significance of serum microRNA (miR)-134-5p and Let-7a in patients with severe preeclampsia (SPE). 
Methods In total, 100 pregnant women with gestational hypertension diagnosed were selected as the research subjects, including 40 pregnant women with preeclampsia (PE) and 60 pregnant women with SPE. Another 100 normal pregnant women who underwent pregnancy examination in our hospital during the same period served as the control group. The real-time quantitative PCR (qRT-PCR) method was applied to detect the relative expression levels of serum miR-134-5p and Let-7a. Pearson method was applied for correlation analysis, and multivariate Logistic regression was applied to analyze the influencing factors of SPE. 
Results There was a significant difference in the serum levels of miR-134-5p and Let-7a among the control group, PE group, and SPE group (F=288.012, 251.780, P＜0.001). Among them, the serum levels of miR-134-5p and Let-7a in the PE group and SPE group were higher than those in the control group (P＜0.05), while the serum levels of miR-134-5p and Let-7a in the SPE group were higher than those in the PE group (P＜0.05). There were significant differences between the PE group and the SPE group with respect to systolic blood pressure (SBP), diastolic blood pressure, urinary protein, creatinine, lactic dehydrogenase, blood urea nitrogen (BUN), mean platelet volume (MPV), albumin (ALB) levels, neonatal length, and neonatal body mass (all P＜0.05). The serum expressionlevel of miR-134-5p in PE patients was negatively correlated with neonatal length (r=-0.608, P＜0.05), but positively correlated with SBP, urinary protein, and lactic dehydrogenase (r=0.613, 0.548, 0.635, all P＜0.05). The expression level of Let-7a was negatively correlated with neonatal length (r=-0.587, P＜0.05), and positively correlated with SBP, urinary protein, and lactic dehydrogenase (r=0.624, 0.571, 0.478, all P＜0.05). The serum expression levels of miR-134-5p and Let-7a in PE patients were significantly and positively correlated (r=0.623, P＜0.001). SBP (OR=1.527, 95%CI: 1.042-2.238), urinary protein (OR=1.825, 95%CI: 1.010-3.299), miR-134-5p (OR=1.467, 95%CI: 1.023-2.104), and Let-7a (OR=1.523, 95%CI: 1.010-2.299) were all risk factors for SPE (P＜0.05). 
Conclusion The serum levels of miR-134-5p and Let-7a in pregnant women with SPE are remarkably elevated. MiR-134-5p and Let-7a are correlated with neonatal length, SBP, urinary protein, and lactic dehydrogenase, and are influencing factors for the occurrence of SPE. 

Key words: eclampsia, miR-134-5p, Let-7a, clinical significance