Objective: To determine frequency, stage and grade of placental histologic acute maternal inflammatory response (MIR) and fetal inflammatory response (FIR) in meconium-stained amniotic fluid (MSAF) in our predominantly African-American population.
Methods: Term placentas with MSAF (n = 310) were evaluated for MIR/FIR, including stage/grade, and compared with placentas with clear amniotic fluid (AF) (n = 250). MIR/FIR were also evaluated in thick compared to thin MSAF subgroups. Selected demographic and clinical features were compared.
Results: MIR and FIR were present in 57.7 and 40.3% of the MSAF compared to 44.0 and 29.2% of the clear AF group, respectively (p = .001 and .008). MIR with FIR was present in 35.8% of the MSAF compared to 25.2% of the clear AF group (p = .008); however, there was no significant difference in frequency of MIR without FIR between groups. There was no significant difference in frequency of MIR/FIR in thick compared to thin MSAF; however, thick MSAF was associated with higher FIR stage compared to thin MSAF (29.2 versus 5.4%, p = .004). This association was not seen with MIR stage or MIR/FIR grade.
Conclusions: Histologic MIR and FIR are frequent findings in MSAF. Thick MSAF is associated with higher FIR stage when compared to thin MSAF.
Keywords: Meconium; meconium-stained amniotic fluid; placenta; placental inflammation; thick meconium.