Zigzag Fetal Heart Rate Pattern in an Uncomplicated Pregnancy with Dual Intrauterine Infection Detected During Labor with Intact Membranes: A Case Report

Background: Histologic chorioamnionitis (HCA) is a placental inflammatory condition characterized by neutrophilic infiltration of the fetal membranes, often occurring without overt clinical signs or symptoms. Risk factors include prolonged labor, premature rupture of membranes (PROM) exceeding 12 h, nulliparity, labor dystocia, and lower socioeconomic status. Although HCA frequently presents as a subclinical condition, its early diagnosis remains challenging. Nevertheless, HCA is associated with an increased risk of maternal and neonatal morbidity, including early-onset neonatal sepsis, cerebral palsy, and long-term neurodevelopmental impairment. We report the case of a 29-year-old primigravida at 40 + 0 weeks of gestation, admitted for decreased fetal movements. Discussion: Cardiotocographic (CTG) monitoring revealed a “zigzag pattern” in the absence of maternal fever, leukocytosis, or tachycardia. Due to the CTG findings suggestive of possible fetal compromise, in addition to reduced fetal movements, an emergency cesarean section was performed. Intraoperative findings included heavily meconium-stained amniotic fluid, then the examination of the placenta confirmed acute HCA with a maternal inflammatory response, without evidence of fetal inflammatory response. Conclusion: This case highlights the crucial role of CTG abnormalities, particularly the “zigzag pattern,” as an early marker of subclinical intrauterine inflammation. Early recognition of such patterns may facilitate timely intervention and improve perinatal outcomes in cases of histologic chorioamnionitis.