{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T15:14:38Z","timestamp":1784128478635,"version":"3.55.0"},"reference-count":27,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2024,5,19]],"date-time":"2024-05-19T00:00:00Z","timestamp":1716076800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J of Obstet and Gynaecol"],"published-print":{"date-parts":[[2024,8]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Aim<\/jats:title><jats:p>For women, being underweight increases their susceptibility to osteoporosis, anemia, and other conditions and affects the weight of their infants and the well\u2010being of future generations. This study examined the association between low pre\u2010pregnancy body mass index (BMI) and low birthweight using health insurance claims data and health checkup data, including weight measurements.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We used health insurance claims data and health checkup data (JMDC, Tokyo, Japan) of women and their newborns in Japan between 2006 and 2020. We used checkup data, which included more accurate weight measurements and blood test\u2010based diagnoses of anemia and hyperlipidemia compared to self\u2010reported data. Maternal pre\u2010pregnancy BMI was compared across three groups: underweight (BMI &lt;18.5\u2009kg\/m<jats:sup>2<\/jats:sup>), normal weight (BMI 18.5\u201324.9\u2009kg\/m<jats:sup>2<\/jats:sup>), and overweight (BMI \u226525.0\u2009kg\/m<jats:sup>2<\/jats:sup>). The primary outcome was low birthweight (&lt;2500\u2009g), and secondary outcome was preterm childbirth. Logistic regression analyses were conducted to compare outcomes in the three groups by BMI. The underweight BMI group was considered as the reference group. A subgroup analysis was performed by maternal age.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>In total, 16\u2009363 mothers (underweight, 3418 [21%], normal weight, 11\u2009493 [70%], and overweight, 1452 [8.9%]) were included. The risk of primary outcome (low birthweight) was significantly lower in the normal weight group than in the underweight group (4.6% vs. 5.7%; adjusted odds ratio 0.78 [95% confidence interval: 0.65\u20130.96]). In the subgroup analyses, no significant differences were noted in the incidences of low birthweight and preterm childbirth between maternal age groups.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Pre\u2010pregnancy BMI was associated with an increased risk of delivering low\u2010birthweight infant. Awareness about the importance of women's pre\u2010pregnancy health and appropriate BMI may reduce the incidence of low birthweight.<\/jats:p><\/jats:sec>","DOI":"10.1111\/jog.15973","type":"journal-article","created":{"date-parts":[[2024,5,20]],"date-time":"2024-05-20T06:53:58Z","timestamp":1716188038000},"page":"1295-1301","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Pre\u2010pregnancy body mass index and low birthweight: Secondary data analysis using health insurance claims data in Japan"],"prefix":"10.1111","volume":"50","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4834-5799","authenticated-orcid":false,"given":"Kana","family":"Fukui","sequence":"first","affiliation":[{"name":"Division of Neonatology National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maiko","family":"Suto","sequence":"additional","affiliation":[{"name":"Division of Health Policy National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3411-5896","authenticated-orcid":false,"given":"Kayoko","family":"Kaneko","sequence":"additional","affiliation":[{"name":"Division of Maternal Medicine National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tetsuya","family":"Isayama","sequence":"additional","affiliation":[{"name":"Division of Neonatology National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yushi","family":"Ito","sequence":"additional","affiliation":[{"name":"Division of Neonatology National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5957-600X","authenticated-orcid":false,"given":"Kenji","family":"Takehara","sequence":"additional","affiliation":[{"name":"Division of Health Policy National Center for Child Health and Development  Tokyo Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2024,5,19]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/s0140-6736(14)60460-8"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1097\/EDE.0b013e31819ed4ed"},{"key":"e_1_2_9_4_1","unstructured":"Japanese Ministry of Health LaW.National Health and Nutrition survey in Japan. 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