{
  "abstract": "Introduction In the USA, studies often show that immigrants exhibit relatively favourable perinatal outcomes compared with their US-born counterparts of the same race/ethnicity, despite socioeconomic and language barriers in healthcare. However, studies with individuals in their home country are limited.Methods and results We analysed 32 028 Japanese who gave singleton births from two data sources: the US vital statistics records (N=19 462) and the Birth and Three-Generation Cohort Study conducted by the Tohoku Medical Megabank Organization (N=12 566) between 2015 and 2017. The US data were divided into two groups based on nativity: the first generation and the second generation and later. Using Japanese women who delivered in Japan as the reference, associations between nativity and perinatal outcomes were evaluated using regression models, with analyses stratified by pre-pregnancy body mass index category. The ORs (95% CI) of preterm birth were higher among Japanese women in the USA (the first generation: 1.20 (1.15 to 1.33); the second generation and later: 1.40 (1.28 to 1.54)), as were the ORs of macrosomia (1.71 (1.48 to 1.98) and 1.98 (1.68 to 2.32), respectively). In contrast, the ORs of term or post-term low birth weight were lower among Japanese women in the USA (0.77 (0.71 to 0.84) and 0.81 (0.71 to 0.91), respectively). The association of nativity on the ORs of low birth weight differed depending on the term of birth.Conclusions Japanese immigrants to the USA have heterogenous risk of perinatal outcomes compared with Japanese who remain in Japan. Including home country data in immigration studies may provide a more detailed understanding of the impact of immigration on their perinatal outcomes.",
  "authors": [
    {
      "affiliations": [
        "Stanford Center for Asian Health Research and Education, Stanford University School of Medicine, Palo Alto, California, USA",
        "Preconception Care Center, Integrated Center for Women’s Health, National Center for Child Health and Development, Setagaya, Tokyo, Japan"
      ],
      "name": "Asako Mito"
    },
    {
      "affiliations": [
        "Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Hasumi Tomita"
    },
    {
      "affiliations": [
        "Center for Maternal and Perinatal Medicine, Tohoku University Hospital, Sendai, Miyagi Prefecture, Japan",
        "Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Noriyuki Iwama"
    },
    {
      "affiliations": [
        "Stanford Center for Asian Health Research and Education, Stanford University School of Medicine, Palo Alto, California, USA"
      ],
      "name": "Shiori Kawai"
    },
    {
      "affiliations": [
        "Department of Pediatrics – Division of Neonatal and Developmental Medicine, Stanford University School of Medicine, Palo Alto, California, USA",
        "California Perinatal Quality Care Collaborative, Palo Alto, California, USA"
      ],
      "name": "Daniel Helkey"
    },
    {
      "affiliations": [
        "Division of Molecular Epidemiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan",
        "Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi Prefecture, Japan",
        "Department of Pharmaceutical Sciences, Tohoku University Hospital, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Taku Obara"
    },
    {
      "affiliations": [
        "Stanford Center for Asian Health Research and Education, Stanford University School of Medicine, Palo Alto, California, USA",
        "Department of Medicine - Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California, USA"
      ],
      "name": "Robert J Huang"
    },
    {
      "affiliations": [
        "Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Hirotaka Hamada"
    },
    {
      "affiliations": [
        "Division of Molecular Epidemiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan",
        "Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi Prefecture, Japan",
        "Department of Pharmaceutical Sciences, Tohoku University Hospital, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Aoi Noda"
    },
    {
      "affiliations": [
        "Division of Molecular Epidemiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan",
        "Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Mami Ishikuro"
    },
    {
      "affiliations": [
        "Division of Molecular Epidemiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan",
        "Department of Preventive Medicine and Epidemiology, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi Prefecture, Japan",
        "Department of Disaster Public Health, International Research Institute of Disaster Science, Tohoku University, Sendai, Miyagi, Japan"
      ],
      "name": "Shinichi Kuriyama"
    },
    {
      "affiliations": [
        "Stanford Center for Asian Health Research and Education, Stanford University School of Medicine, Palo Alto, California, USA"
      ],
      "name": "Fumiaki Ikeno"
    },
    {
      "affiliations": [
        "Preconception Care Center, Integrated Center for Women’s Health, National Center for Child Health and Development, Setagaya, Tokyo, Japan"
      ],
      "name": "Naoko Arata"
    },
    {
      "affiliations": [
        "Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan",
        "Department of Maternal and Fetal Therapeutics, Tohoku University Graduate School of Medicine, Sendai, Miyagi Prefecture, Japan"
      ],
      "name": "Masatoshi Saito"
    },
    {
      "affiliations": [
        "Stanford Center for Asian Health Research and Education, Stanford University School of Medicine, Palo Alto, California, USA",
        "Department of Medicine - Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, USA"
      ],
      "name": "Latha Palaniappan"
    },
    {
      "affiliations": [
        "Department of Medicine - Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, USA"
      ],
      "name": "Adrian M Bacong"
    }
  ],
  "title": "Cross-country comparison of perinatal outcomes between japanese mothers in the united states and japan: a cross-sectional study",
  "uid": "36f71a17-c74d-59f3-b213-0a8210174a29"
}