{"title":"Maternal obesity and the incidence of large-for-gestational-age newborns in isolated hypothyroxinemia pregnancies: a comparative cohort study.","authors":"Bin Zhang, Sijie Xi, Zhaolong Zhan, Yinglu Zhang, Fengying Lu, Xiaosong Yuan","doi":"10.1186/s12958-025-01394-z","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>The synergistic impact of isolate maternal hypothyroxinaemia (IMH) and other modulators on fetal growth outcomes is unknown. This study was aimed to determine whether third trimester IMH [free thyroxine level (FT4) below the the 5th percentile and thyroid stimulating hormone (TSH) between the 5th and 95th percentiles] and prenatal body mass index (BMI) jointly increase the risk of large for gestational age (LGA) deliveries.</p><p><strong>Methods: </strong>A retrospective analysis was conducted on 11,478 Chinese pregnant women with laboratory data (including thyroid hormone levels and routine biochemical tests) and hospitalization records from a specialized hospital.</p><p><strong>Results: </strong>The prevalence of obesity (BMI ≥ 30 kg/m<sup>2</sup>) and IMH was 20.1% (2312/11478) and 4.5% (519/11478), retrospectively. Women with obesity had a 6.96-fold greater risk of IMH (95% CI: 4.58, 10.58) and a 5.88-fold increased risk of LGA (95% CI: 4.87, 7.11) than those with normal weight (BMI < 25 kg/m<sup>2</sup>), while women with IMH had a 1.32-fold increased risk of LGA (95% CI: 1.05, 1.65) than euthyroid women. The positive associations of LGA risk with obesity and IMH remained robust in sensitivity analyses conducted among women aged < 35 years, primiparas, and those without pregnancy complications. Compared to euthyroid women with normal weight, women with obesity and IMH had a 7.60-fold higher risk of LGA (95% CI: 5.26, 10.97). Additionally, a significant interaction between BMI categories and IMH on LGA was observed (P < 0.013). Subgroup analyses validated this interaction among women with aged < 35 years, multiparity, and non-pregnancy complications.</p><p><strong>Conclusions: </strong>Obesity and IMH in late pregnancy are both associated with an increased risk of LGA newborns, and their coexistence may further amplifies this risk; prenatal BMI and thyroid hormone levels could serve as potential indicators for identifying individuals at elevated LGA risk.</p>","PeriodicalId":21011,"journal":{"name":"Reproductive Biology and Endocrinology","volume":"23 1","pages":"60"},"PeriodicalIF":4.7000,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12013030/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Reproductive Biology and Endocrinology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1186/s12958-025-01394-z","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENDOCRINOLOGY & METABOLISM","Score":null,"Total":0}
引用次数: 0
Abstract
Background: The synergistic impact of isolate maternal hypothyroxinaemia (IMH) and other modulators on fetal growth outcomes is unknown. This study was aimed to determine whether third trimester IMH [free thyroxine level (FT4) below the the 5th percentile and thyroid stimulating hormone (TSH) between the 5th and 95th percentiles] and prenatal body mass index (BMI) jointly increase the risk of large for gestational age (LGA) deliveries.
Methods: A retrospective analysis was conducted on 11,478 Chinese pregnant women with laboratory data (including thyroid hormone levels and routine biochemical tests) and hospitalization records from a specialized hospital.
Results: The prevalence of obesity (BMI ≥ 30 kg/m2) and IMH was 20.1% (2312/11478) and 4.5% (519/11478), retrospectively. Women with obesity had a 6.96-fold greater risk of IMH (95% CI: 4.58, 10.58) and a 5.88-fold increased risk of LGA (95% CI: 4.87, 7.11) than those with normal weight (BMI < 25 kg/m2), while women with IMH had a 1.32-fold increased risk of LGA (95% CI: 1.05, 1.65) than euthyroid women. The positive associations of LGA risk with obesity and IMH remained robust in sensitivity analyses conducted among women aged < 35 years, primiparas, and those without pregnancy complications. Compared to euthyroid women with normal weight, women with obesity and IMH had a 7.60-fold higher risk of LGA (95% CI: 5.26, 10.97). Additionally, a significant interaction between BMI categories and IMH on LGA was observed (P < 0.013). Subgroup analyses validated this interaction among women with aged < 35 years, multiparity, and non-pregnancy complications.
Conclusions: Obesity and IMH in late pregnancy are both associated with an increased risk of LGA newborns, and their coexistence may further amplifies this risk; prenatal BMI and thyroid hormone levels could serve as potential indicators for identifying individuals at elevated LGA risk.
期刊介绍：
Reproductive Biology and Endocrinology publishes and disseminates high-quality results from excellent research in the reproductive sciences.
The journal publishes on topics covering gametogenesis, fertilization, early embryonic development, embryo-uterus interaction, reproductive development, pregnancy, uterine biology, endocrinology of reproduction, control of reproduction, reproductive immunology, neuroendocrinology, and veterinary and human reproductive medicine, including all vertebrate species.
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