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Comparative Study
. 2025 Mar 22;15(1):9943.
doi: 10.1038/s41598-025-92393-y.

Comparative analysis of necrotizing enterocolitis in preterm infants born in Japan and born to mothers of Japanese ethnicity in California

Satoshi Kusuda  1   2 , Mihoko V Bennett  3 , Jeffrey B Gould  3 ; Neonatal Research Network of Japan
Collaborators, Affiliations
Comparative Study

Comparative analysis of necrotizing enterocolitis in preterm infants born in Japan and born to mothers of Japanese ethnicity in California

Satoshi Kusuda et al. Sci Rep. .

Abstract

Infants born in Japan are reported to have a low incidence of necrotizing enterocolitis (NEC) among countries, and these differences remained significant after adjusting for common clinical factors. To investigate the impact of ethnic background, we compared the incidence of NEC between infants born in Japan and those born to mothers of Japanese ethnicity in California. Preterm infants born between 2008 and 2019 at 22-29 weeks of gestational age were analyzed retrospectively. Four groups were analyzed: infants born in Japan (JP), infants born in California to mothers born in Japan (JP-J), infants born in California to mothers with Japanese ethnicity but born in the United States or another country (JP-CA), and a comparison group of infants born in California to non-Hispanic White mothers (NHW-CA). Each cohort consisted of 52,049, 115, 226, and 12,275 infants, respectively. Unadjusted NEC incidences were significantly lower in JP compared to the other three cohorts (1.7% JP, 4.5% JP-J, 4.6% JP-CA, and 3.3% NHW-CA, respectively; p < 0.01). After adjusting for confounding factors, odds ratios for NEC in JP vs. JP-J, JP-CA, and NHW-CA were 3.04 (1.18-7.80), 2.89 (1.45-5.75), and 1.96 (1.56-2.47), respectively. This study suggests that differences in NEC incidence in Japan are not explained by ethnicity.Clinical trial regstration number: Registration numbers is UMIN000006961 ( https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000008217 ) for the Neonatal Research Network of Japan. However, the the California Perinatal Quality Care Collaborative (CPQCC) aims only to assess neonatal outcomes for the purpose of quality assessment and improvement. So, no clinical trial number is available. Please refer to the web site https://www.cpqcc.org/ .

Keywords: Epidemiology; Ethnicity; Extremely preterm infants; Genetic background; Incidence; Mortality; Practices.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Patient flow. NRNJ: the Neonatal Research Network of Japan CPQCC: the California Perinatal Quality Care Collaborative GA: gestational age.
Fig. 2
Fig. 2
Necrotising enterocolitis, spontaneous gastrointestinal perforation, and death/necrotizing enterocolitis rates among different cohorts. NEC and its composite outcome in preterm infants born in Japan were significantly lower than all other cohorts in California (unadjusted logistic regression, p < 0.01). Although spontaneous intestinal perforation was lowest in non-Hispanic White infants, there was no significant difference among cohorts. (Refer to Table 2). Vertical bars show 95% confidential limits. NEC: necrotizong enterocolitis, SIP: spontanous intestinal perforation JP: Japan, CA: California, NHW: non-Hispanic White.
Fig. 3
Fig. 3
Trends in necrotizing enterocolitis in Japan and California. Comparison of annual trends in incidences in three groups revealed no significant differences for Japan (Cochran-Armitage trend test), while significant decreases for the CPQCC (p < 0.01) and non-Hispanic White infants born in California (p < 0.01). The NEC incidences in each year group are described at the bottom of the figure. CPQCC: the California Perinatal Quality Care Collaborative, NHW-CA: non-Hispanic White infants in Calfornia, JP: infants born in Japan.
See this image and copyright information in PMC

References

    1. Bell, E. F. et al. Mortality, in-hospital morbidity, care practices, and 2-year outcomes for extremely preterm infants in the US, 2013–2018. JAMA.327, 248–263. 10.1001/jama.2021.23580 (2022). - PMC - PubMed
    1. Helenius, K. et al. Survival in very preterm infants: An international comparison of 10 national neonatal networks. Pediatrics.140, e20171264. 10.1542/peds.2017-1264 (2017). - PubMed
    1. Nakanishi, H., Suenaga, H., Uchiyama, A., Kono, Y. & Kusuda, S. Trends in the neurodevelopmental outcomes among preterm infants from 2003–2012: a retrospective cohort study in Japan. J Perinatol.38, 917–928. 10.1038/s41372-018-0061-7 (2018). - PubMed
    1. Lee, H. C., Liu, J., Profit, J., Hintz, S. R. & Gould, J. B. Survival without major morbidity among very low birth weight infants in California. Pediatrics.146, e20193865. 10.1542/peds.2019-3865 (2020). - PMC - PubMed
    1. Stoll, B. J. et al. Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993–2012. JAMA.314, 1039–1051. 10.1001/jama.2015.10244 (2015). - PMC - PubMed

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