Tohoku J. Exp. Med., 2017 December, 243(4)

Histological Chorioamnionitis as a Risk Factor for Preterm Birth without Disturbing Fetal Heart Rate: A Case-Control Study

HYO KYOZUKA,¹ SYUN YASUDA,¹ TSUYOSHI HIRAIWA,¹ MAKIHO ISHIBASHI,¹ KATSUHIKO KATO² and KEIYA FUJIMORI¹

¹Department of Obstetrics and Gynecology, School of Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan
²Department of Obstetrics and Gynecology, Fukushima National Hospital, Sukagawa, Fukushima, Japan

Histological chorioamnionitis (CAM) is one form of intrauterine inflammation that is often seen in cases of preterm birth and are usually confirmed based on pathological examination after delivery. Histological CAM is related to significant neonatal morbidity and mortality; however, its etiology is unknown. The objective of this study was to determine the risk factors for histological CAM, using medical background, including fetal heart rate (FHR) patterns in preterm birth cases. The preterm birth cases delivered between 28 and 36 weeks were categorized into two groups according to the presence of histological CAM. Ninety-five preterm infants were included: 48 infants without histological CAM and 47 cases with histological CAM. The odds ratio for histological CAM was adjusted for FHR patterns, gestational age, and delivery mode (vaginal delivery or Caesarean section). Logistic regression analysis showed that vaginal delivery and gestational age were associated with histological CAM (odds Ratio [OR]: 3.1, 95% confidence interval [CI]: 1.0-9.4, p < 0.05, and OR: 0.8, 95% CI: 0.6-0.9, p < 0.05, respectively). However, there were no specific FHR patterns associated with histological CAM. Our study indicates that in preterm birth cases, histological CAM is not related to any specific FHR pattern. However, labor uterine contraction and immature gestational age at the delivery are related to histological CAM. These results may provide better delivery management methods for preterm birth cases.

keywords —— chorioamnionitis; delivery mode; fetal heart rate pattern; intrauterine inflammation; preterm birth

© 2017 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2017, 243, 289-295

Correspondence: Hyo Kyozuka, M.D., Department of Obstetrics and Gynecology, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan.

e-mail: Kyozuka@fmu.ac.jp