Placental miRNAs Targeting Cellular Stress Response Pathways Are Highly Expressed in Non-Hispanic Black People.

Non-Hispanic Black (NHB) people have a 2.5-fold higher risk of maternal mortality when compared to non-Hispanic White (NHW) people. Neonates of NHB people are more likely to be born preterm and small for gestational age, which may be driven by structural racism. The placenta is very sensitive to the maternal environment and may play a critical role in the translation of environmental stressors to pregnancy outcomes. Our aim was to assess the placental miRNA expression profile in both NHB and NHW people and the association between differentially expressed miRNAs and pregnancy outcomes. Placentas were collected from 50 NHB and 74 NHW people with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. Placental miRNA expression was measured via whole-genome small RNA-sequencing in a subset of 77 placentas. Fifteen miRNAs were more highly expressed in the placentas of NHB people. Several of these miRNAs were associated with cellular stress response pathways, suggesting that they may be responding to environmental stressors. Placental miR-192-5p expression was lower among NHB people and was positively associated with neonatal adiposity, suggesting it may be sensitive to structural racism with potential impacts on fetal growth.