Circulating microRNA patterns differ in early-onset but not late-onset pre-eclampsia

Women with early-onset pre-eclampsia carried roughly three times as much of a hypoxia-sensitive microRNA in their blood as healthy pregnant women with similar gestational ages, according to a small single-center pilot study published in Archives of Gynecology and Obstetrics. In contrast, women with late-onset pre-eclampsia showed no meaningful difference in either of the two microRNAs examined, miR-210-3p and miR-518b, compared with their own matched controls. The finding is notable because most earlier studies of circulating microRNAs in pre-eclampsia pooled cases across gestational ages, leaving open whether the two clinically distinct forms of the disease share the same molecular signature in maternal blood.

The study, led by Isabel Hoffmann, Jochen Maurer, Christian Enzensberger, Elmar Stickeler and Oliver Graupner, enrolled ten women with early-onset pre-eclampsia and eight women with late-onset pre-eclampsia, each compared with a separate group of gestational-age-matched healthy pregnant controls. Early-onset disease was strictly defined: all affected women delivered before 34 weeks and 0 days of gestation and had developed severe features during pregnancy according to national German (AWMF) and international (ISSHP and NICE) guidelines. The mean gestational age at sampling was 28 weeks and 2 days in the early-onset cases versus 30 weeks and 6 days in their controls, while the late-onset cohort and its controls were both sampled at a mean of 37 weeks and 0 days.

Pre-eclampsia itself was defined by standard criteria: elevated blood pressure of at least 140 mmHg systolic or 90 mmHg diastolic on two occasions at least four hours apart, together with at least one additional feature such as proteinuria of 300 mg per 24 hours, thrombocytopenia with platelets below 100,000 per microliter, elevated liver transaminases to twice the normal concentration, new-onset renal insufficiency with serum creatinine of at least 0.9 mg/dl, pulmonary edema, new-onset cerebral or visual disturbances, fetal growth restriction, or an elevated sFlt-1/PlGF ratio. Notably, 80 percent of the early-onset cases also had associated early-onset fetal growth restriction, a detail that turned out to be central to interpreting the results.

The researchers chose two microRNAs that are among the most frequently reported pre-eclampsia-associated molecules in the literature. miR-210-3p is the best-studied microRNA in pre-eclampsia and is known as a hypoxia-responsive microRNA, playing important roles in angiogenesis, trophoblast proliferation and differentiation; it has been found upregulated in both placental tissue and maternal blood in previous studies. miR-518b belongs to the chromosome 19 microRNA cluster, which is increasingly expressed in placental trophoblast cells and is involved in placentation. miR-518b interacts with the early growth response protein 1 (EGR-1), a zinc-finger transcription factor important for angiogenesis, cell differentiation and migration, and its dysregulation has been shown to decrease EGR1 and vascular endothelial growth factor, inhibiting trophoblast cell migration and angiogenesis.

Methodologically, the team collected a single serum sample containing 7.5 ml of whole blood from each mother at the time of pre-eclampsia diagnosis. Samples were allowed to coagulate fully, centrifuged at 2500 × g for 10 minutes, aliquoted and stored at −80 °C. RNA was isolated with the miRNeasy Mini Kit, and complementary DNA was synthesized using a TaqMan Advanced cDNA Synthesis Kit. A synthetic spike-in control, ath-miR-159a, a microRNA absent from human samples, was added in equal amounts to each specimen before extraction to control for extraction efficiency and inter-sample variability. Quantification was performed by real-time PCR on a Roche LightCycler 480 instrument, with each assay run in technical triplicates. The spike-in showed consistent recovery across cohorts, with mean Ct values of 17.71 ± 0.26 in the late-onset cohort and 17.75 ± 0.38 in the early-onset cohort.

The analysis used the delta Ct method, in which lower values indicate higher microRNA concentrations, because each unit difference in delta Ct corresponds to a roughly twofold difference in relative expression. Statistical comparisons were made on delta Ct values using the Mann–Whitney U test, with Bonferroni correction for the two microRNAs tested within each cohort, setting the adjusted significance threshold at 0.025. Because the exploratory pilot study was small, the authors also reported Hodges–Lehmann estimators with 95 percent confidence intervals alongside p-values. An analysis of covariance tested whether residual gestational age differences influenced the results, and a sensitivity analysis excluded two early-onset patients with pre-existing hypertension and gestational diabetes, conditions that could not be modeled as covariates because they occurred only in cases.

The headline result concerned miR-210-3p in early-onset disease. Mean delta Ct values were 7.63 ± 1.1 in cases versus 9.31 ± 1.9 in controls, corresponding to a mean fold change of 3.2, with p = 0.019 against the adjusted threshold of 0.025 and a Hodges–Lehmann estimator of 1.23 (95 percent CI 0.15 to 2.66). miR-518b showed a numerical, non-significant difference in the same cohort, with mean fold change of 2.1 (8.77 ± 1.4 vs. 9.85 ± 1.8; p = 0.19; HL 0.70, 95 percent CI −0.33 to 2.41). In the late-onset cohort, neither microRNA differed from controls: miR-210-3p measured 8.20 ± 1 versus 7.48 ± 1.2 (p = 0.16; HL −0.73, 95 percent CI −2.2 to 0.78) and miR-518b measured 9.82 ± 1.1 versus 9.60 ± 0.9 (p = 0.80; HL −0.14, 95 percent CI −1.61 to 0.91).

The sensitivity analysis told a more cautious story. When the two patients with chronic hypertension and gestational diabetes were excluded, the difference in miR-210-3p between early-onset cases and controls kept the same direction and pattern but was no longer statistically significant (p = 0.067). The adjusted analyses found no statistically significant association between gestational age and the expression of either microRNA, and in the late-onset cohort none of the covariates tested—gestational age, hypertension and diabetes—showed significant associations. The authors also noted that individual expression levels varied considerably within each group and overlapped between cases and controls, meaning the measured differences may not reliably distinguish an individual patient from a healthy pregnant woman.

That overlap, combined with the composition of the early-onset cohort, shapes how the findings should be read. Because miR-210-3p responds to hypoxia and has been shown in placental studies of early-onset pre-eclampsia and fetal growth restriction to reflect shared placental pathology, and because 80 percent of the early-onset cases here also had early-onset fetal growth restriction, the authors state that their results cannot differentiate whether the elevated circulating miR-210-3p is primarily related to early-onset pre-eclampsia, to the concurrent growth restriction, or to the underlying placental dysfunction. They also caution that miR-210 has been reported to increase in hypertension and potentially in gestational diabetes, so specificity for pre-eclampsia remains uncertain. The absence of a comparator group with isolated early-onset fetal growth restriction, the lack of an endogenous reference microRNA, the small sample size with no prior sample size calculation, and the absence of clinical follow-up data are all listed as limitations.

The authors frame the work as exploratory and emphasize that larger studies are needed to determine whether these microRNAs hold promise as biomarkers. They argue that the study’s strengths lie in its clearly defined early-onset and late-onset populations based on guideline diagnostic criteria, the inclusion of established anti-angiogenic markers such as the sFlt-1/PlGF ratio, and blood sampling timed to diagnosis, which they consider more representative of everyday clinical practice than postpartum placental tissue testing. They also note that reference values for microRNA concentrations across normal gestation remain largely unknown, and that without a clear discriminatory threshold the clinical use of these microRNAs as standalone diagnostic tools is limited. For now, the message is measured: a threefold difference in a hypoxia-linked microRNA marks early-onset disease in this pilot cohort, but it does not yet amount to a diagnostic test, and the late-onset form of the disease left no such molecular trace in maternal serum.

Subject of Research: Circulating microRNA expression in early-onset versus late-onset pre-eclampsia

Article Title: Expression patterns of circulating microRNA in confirmed early-onset and late-onset pre-eclampsia cases

Article References: Hoffmann, I., Maurer, J., Enzensberger, C., Stickeler, E., & Graupner, O. (2026). Expression patterns of circulating microRNA in confirmed early-onset and late-onset pre-eclampsia cases. Archives of Gynecology and Obstetrics, 313(1), Article 279. https://doi.org/10.1007/s00404-026-08583-0

Image Credits: AI Generated

DOI: 10.1007/s00404-026-08583-0

Keywords: pre-eclampsia, microRNA, miR-210-3p, miR-518b, early-onset pre-eclampsia, late-onset pre-eclampsia, fetal growth restriction, placental dysfunction, serum biomarkers, real-time PCR, pilot study, pregnancy