Maternal serum microRNAs not predictive of preterm birth
1. MicroRNA profiles were not significantly different between women who did and did not experience preterm delivery.
 2. Expression of mIR-200a* was decreased in women with preterm birth.
Evidence Rating Level: 3 (Average)
Study Rundown: Preterm birth, delivery before 37 weeks gestation, impacts over 10% of births in the United States. Risk factors include history of prior preterm delivery or abortion, short inter-pregnancy interval and short cervical length. Sonographic evaluation of cervical length along with cervical exam, when appropriate, are used to assess cervical insufficiency, and the fetal biomarker fetal fibronectin can be used to predict premature preterm rupture of membranes, both of which aid in prediction of the risk for delivery within the next 7 or 14 days. Researchers continue to explore biomarkers that may identify high-risk women earlier in pregnancy to improve maternal and fetal outcomes. More recently, scientists have become increasingly interested in the role of microRNAs (miRNAs), which are small non-coding RNA molecules that regulate gene expression inversely (i.e. increased miRNA expression represses target genes). The authors previously observed that miRNA expression in cervical cells differs between women who do and those who do not experience preterm delivery. In the present work they sought to evaluate whether maternal serum miRNAs also differed by preterm birth and found that they did not.
The main strength of the study was prospective data collection. Weaknesses included case-control design, small sample size and non-matched controls, which limit the study’s validity and ability to formulate conclusions about causality. Additionally, only patients with symptoms of preterm labor were included, which limits external validity. Further analysis of new miRNA sequences in both local and systemic tissues are necessary to aid in detection of a biomarker that predicts preterm birth earlier in pregnancy.
Click to read the study in AJOG
Relevant Reading: The role and challenges of biomarkers in spontaneous preterm birth and preeclampsia
In-Depth [case-control study]: This study evaluated miRNA profiles of women presenting for evaluation of preterm delivery who delivered at <30 weeks (n=40) and ≥37 weeks (n=40). The exposures of interest were variations in the expression of 5640 miRNA sequences.
Among women who experienced preterm delivery, the expression of miR-200a* was decreased (p=0.0001) and expression of miR-4695-5p (p=0.002), miR-665 (p=0.001) and miR-887 (p=0.0004) were increased compared to women who delivered at or after term. There was a less than 2-fold change in expression for these four miRNAs.
More from this author: Turmeric associated with fewer neural tube defects in mice, Pregnancy associated with postpartum vascular changes, Similar outcomes after supracervical vs. total hysterectomy, Less wound complications with suture skin closure after C-section, Preeclampsia linked to autism and developmental delay
Image: PD
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