Significant reduction in intrapartum-related perinatal brain injury in infants born at ≥35 weeks' gestation: A regional population-based study over 15 years

Koutarou Doi; Yuki Kodama; Satoshi Matsuzawa; Tomoko Goto; Junsuke Muraoka; Midori Fujisaki; Naoshi Yamada; Hajime Taniguchi; Ken Furuta; Yasuyuki Kawagoe; Masatoki Kaneko; Shinji Katsuragi; Tsuyomu Ikenoue; Hiroshi Sameshima

doi:10.1016/j.earlhumdev.2026.106495

Significant reduction in intrapartum-related perinatal brain injury in infants born at ≥35 weeks' gestation: A regional population-based study over 15 years

Early Hum Dev. 2026 Jan 30:216:106495. doi: 10.1016/j.earlhumdev.2026.106495. Online ahead of print.

Affiliations

¹ Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan. Electronic address: koutarou.doi@med.miyazaki-u.ac.jp.
² Department of Obstetrics and Gynecology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
³ Department of Obstetrics and Gynecology, Koga General Hospital, Miyazaki, Japan.
⁴ Department of Obstetrics and Gynecology, National Hospital Organization Miyakonojo Medical Center, Miyakonojo, Japan.
⁵ Miyazaki Prefectural Nursing University, Miyazaki, Japan.
⁶ Graduate School of Nursing, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
⁷ Kyushu University of Health and Welfare, Nobeoka, Japan.

PMID: 41633003
DOI: 10.1016/j.earlhumdev.2026.106495

Abstract

Objective: The ultimate goal of perinatal care is to ensure that infants survive without neurological impairment. Despite advances in medical technology and healthcare systems that have markedly decreased perinatal mortality, cerebral palsy has shown only a gradual decline in recent population-based studies. The aim of this study was to use a pathway classification system to analyze brain injury cases detected at or beyond 35 weeks' gestation and to clarify temporal changes in the incidence and causal pathways of intrapartum brain injury and its contributing factors in Miyazaki Prefecture, Japan.

Methods: Of 151,558 births recorded in Miyazaki Prefecture from 2001 to 2015, 303 cases of brain injury were registered in the regional perinatal case-review system. Of these, 134 were detected at ≥35 weeks. Brain injury was categorized as congenital anomalies, antepartum, intrapartum, or neonatal onset. Each case was further classified using a pathway system that considered distal and proximal risk factors. Temporal trend analysis was performed across three consecutive 5-year intervals (2001-2005, 2006-2010, and 2011-2015).

Results: Of the 134 cases, 25% were classified as intrapartum-related, 23% as antepartum-related, and 5% as neonatal-related. Overall, the incidence of brain injury at ≥35 weeks decreased significantly over time. Significant downward trends were observed in total cases and intrapartum-related brain injury, with the reduction in intrapartum cases being especially pronounced. Antepartum-related brain injury declined more gradually. Further analysis revealed that the incidence of hypoxia-related intrapartum brain injuries decreased over time, whereas bacterial infection-related intrapartum cases were observed only in the earliest epoch.

Conclusions: This population-based study identified temporal changes in perinatal brain injury detected at or beyond 35 weeks' gestation over 15 years. The incidence of perinatal brain injury declined significantly, particularly intrapartum-related cases with hypoxia-related injury. These improvements might reflect advances in regionalized perinatal care, the establishment of perinatal centers, or multidisciplinary education and training. Further efforts to optimize intrapartum assessment and management would contribute to continued reductions in severe perinatal brain injury.

Keywords: Cerebral palsy; Fetal heart rate monitoring; Hypoxia; Intrapartum brain injury; Perinatal outcomes; Population-based study.