Association of non-reassuring fetal heart rate and fetal acidosis with placental histopathology.

Objective: To investigate the association between different placental lesions and non-reassuring fetal heart rate (NRFHR) pattern and fetal acidosis in labor.
Study Design: Placentas from 213 women who underwent cesarean section because of NRFHR with or without fetal acidosis (pH < 7.2) were classified by histopathologic findings: consistent with maternal circulation abnormalities i.e., namely, marginal or retroplacental hemorrhage (M0), maternal underperfusion, vascular (M1) or villous changes (M2), and those consistent with fetal thrombo-occlusive disease due to vascular (F1) or villous (F2) changes. Lesions were also analyzed by maternal (MIR) or fetal (FIR) origin of inflammatory responses.
Results: Cord blood pH was normal in 169 neonates (7.29 ± 0.04; control group) and <7.2 in 44 (7.10 ± 0.07; study group). The study group had higher rates of histologic chorioamnionitis; MIR was detected in 34.1% compared to17.8% of controls (p = 0.018), and FIR, in 18.2% compared to 6.5% (p = 0.016). Neonates in the study group had lower Apgar scores and longer hospitalization.
Conclusions: Placental MIR and FIR are associated with cord blood acidosis in neonates delivered by cesarean section for NRFHR tracings in labor.
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