Decreased miR-143 and increased miR-21 placental expression levels are associated with macrosomia

Macrosomia, a birth weight ≥ 4,000 g, is associated with maternal and infant health problems. The dysregulation of microRNAs (miRNAs) in the placenta is associated with adverse birth outcomes, yet whether aberrantly expressed placental miRNAs are associated with macrosomia remains unknown. The aim of the current study was to characterize the expression of three placental miRNAs (miR‑6, ‑21 and ‑143) and evaluate their association with macrosomia. The miRNA expression in placental tissues from 67 macrosomic pregnancies and 64 normal pregnancies were analyzed using reverse transcription‑quantitative polymerase chain reaction. The expression of miR‑21 was observed to be elevated in macrosomic placenta compared with control samples, while miR‑143 expression was significantly lower than in control placenta (P<0.05). No significant differences were identified in the miR‑16 expression levels between the groups (P=0.955). Following division of miRNA expression levels by quartile, logistic regression models demonstrated that the odds of macrosomia increased with miR‑21 expression quartile: Q2, odds ratio (OR)=6.67 [95% confidence interval (CI), 1.39‑32.05]; Q3, OR=4.10 (95% CI, 0.88‑19.11); Q4, OR=16.19 (95% CI, 2.46‑106.68). Conversely, higher levels of miR‑143 expression were protective against macrosomia: Q2, OR=0.22 (95% CI, 0.049‑0.98); Q3, OR=0.11 (95% CI, 0.024‑0.55), and Q4, OR=0.16 (95% CI, 0.032‑0.79). Thus, statistical analysis demonstrated that high levels of miR‑21 expression and low levels of miR‑143 expression predict the risk for macrosomia, indicating an interaction between the two miRNAs. Bioinformatic analysis suggested that they are likely to function in the mitogen‑activated protein kinases signaling pathway to influence the risk of macrosomia. The results of the present study provide evidence that placental miR-21 and -143 are important in the formation of macrosomia.