{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T04:47:22Z","timestamp":1776919642254,"version":"3.51.2"},"reference-count":46,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T00:00:00Z","timestamp":1776902400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Nutr."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Male infants exhibit a higher risk of iron deficiency (ID) than females, yet the underlying mechanisms remain unclear. Given that rapid postnatal growth may deplete iron stores and males typically experience faster early development, this study aimed to test whether rapid weight gain (WG) during the first 6\u202fmonths mediates the association between male sex and ID risk at 6\u202fmonths.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We conducted a retrospective cohort study of healthy term infants born at Sichuan Provincial Women\u2019s and Children\u2019s Hospital in Chengdu, China, between January 2023 and June 2024. Associations among sex, WG, and ID were examined using logistic regression, adjusting for selected covariates and feeding type. Mediation analysis used SPSS PROCESS macro (Model 4) to estimate the indirect effect of sex on ID via WG with bootstrapped 95% confidence intervals.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      This study included 355 infants (55.5% male), with a median WG of 4.9\u202fkg. Total ID occurred in 22.5% of infants, with the highest incidence observed in exclusively breastfed males (36%). After adjusting for covariates and feeding type, male infants exhibited greater WG than females (\n                      <jats:italic>\u03b2<\/jats:italic>\n                      \u202f=\u202f0.61\u202fkg, 95%CI: 0.44 to 0.78,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.001) and had higher odds of ID (aOR\u202f=\u202f2.13, 95%CI: 1.23 to 3.70,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.007). Further adjustment for WG attenuated the sex-ID association (aOR\u202f=\u202f1.57, 95%CI: 0.88 to 2.83,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.129), while WG remained independently associated with ID risk (aOR\u202f=\u202f1.63 per kg, 95%CI: 1.17 to 2.27,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f0.004). Mediation analyses revealed that WG partially mediated this association (indirect effect\u202f=\u202f0.30; bootstrapped 95% CI: 0.11 to 0.54), accounting for 40% of the total effect.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Male infants exhibited elevated ID risk at 6\u202fmonths, with postnatal greater WG partially explaining this association. Our findings underscore the need for sex-specific guidelines on the introduction of complementary foods and on iron supplementation, particularly for rapidly growing, exclusively breastfed males before 6\u202fmonths. Prospective trials should evaluate iron dosing strategies aligned with growth trajectories before clinical implementation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fnut.2026.1829613","type":"journal-article","created":{"date-parts":[[2026,4,23]],"date-time":"2026-04-23T04:22:19Z","timestamp":1776918139000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Male sex and iron deficiency risk at 6\u202fmonths: the mediating role of rapid weight gain"],"prefix":"10.3389","volume":"13","author":[{"given":"Dongmei","family":"Ge","sequence":"first","affiliation":[{"name":"Department of Child Health Care, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jing","family":"Nie","sequence":"additional","affiliation":[{"name":"Department of Child Health Care, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanyan","family":"Shi","sequence":"additional","affiliation":[{"name":"Department of Clinical Laboratory, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chunrong","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Obstetrics, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wei","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Child Health Care, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jing","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Obstetrics, Sichuan Provincial Women's and Children's Hospital, The Affiliated Women's and Children's Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]},{"name":"Center of Women\u2019s and Children\u2019s Health Medical Research and Technology Innovation, Sichuan Provincial Women\u2019s and Children\u2019s Hospital, The Affiliated Women\u2019s and Children\u2019s Hospital of Chengdu Medical College","place":["Chengdu, Sichuan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,23]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"e627","DOI":"10.1016\/s2214-109x(22)00084-5","article-title":"National, regional, and global estimates of anaemia by severity in women and children for 2000-19: a pooled analysis of population-representative data","volume":"10","author":"Stevens","year":"2022","journal-title":"Lancet Glob Health"},{"key":"ref2","volume-title":"WHO Global Anaemia Estimates, 2021 Edition: Anaemia in women and children","year":"2021"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"886","DOI":"10.3760\/cma.j.issn.0578-1310.2004.12.104","article-title":"Prevalence of iron deficiency in children aged 7 months to 7 years in China","volume":"42","year":"2004","journal-title":"Chin J 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