{"id":23329,"date":"2026-02-03T15:37:05","date_gmt":"2026-02-03T20:37:05","guid":{"rendered":"https:\/\/www.ices.on.ca\/?post_type=journal_article&p=23329"},"modified":"2026-02-25T15:45:01","modified_gmt":"2026-02-25T20:45:01","slug":"hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality","status":"publish","type":"journal_article","link":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/","title":{"rendered":"Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study"},"content":{"rendered":"

Background<\/strong> \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal outcomes in high-income countries is largely unknown.<\/p>\n

Objective<\/strong> \u2014 To assess early pregnancy hemoglobin concentration and associated severe neonatal morbidity and mortality (SNM-M) in a high-income setting.<\/p>\n

Design<\/strong> \u2014 Population-based, retrospective cohort study.<\/p>\n

Setting<\/strong> \u2014 Ontario, Canada, where health care is publicly funded.<\/p>\n

Participants<\/strong> \u2014 Women aged 18 to 50 years with a singleton birth between 2007 and 2023 and hemoglobin measurement at 2 to 12 weeks\u2019 gestation.<\/p>\n

Measurements<\/strong> \u2014 The nonlinear relation between early pregnancy hemoglobin concentration and SNM-M was analyzed in 1-g\/L increments using restricted cubic splines, with 125 g\/L as the referent. The primary outcome was a validated composite measure of SNM-M (major neonatal conditions and critical interventions) up to 27 days after birth. Relative risks (RRs) were adjusted (aRR) for maternal demographic characteristics and chronic conditions.<\/p>\n

Results<\/strong> \u2014 A total of 1\u2009100\u2009341 births were included. A U-shaped relation was observed between early pregnancy hemoglobin concentration and SNM-M. For example, relative to a hemoglobin value of 125 g\/L and a corresponding SNM-M rate of 6.7%, the aRR for SNM-M was 1.08 (95% CI, 1.04 to 1.11) at a hemoglobin concentration of 105 g\/L and 1.17 (CI, 1.10 to 1.25) at 90 g\/L. The aRR for SNM-M was 1.05 (CI, 1.03 to 1.07) at a hemoglobin concentration of 135 g\/L and 1.20 (CI, 1.16 to 1.24) at 150 g\/L.<\/p>\n

Limitation<\/strong> \u2014 Iron replacement status before and during pregnancy was unknown, and residual confounding may influence observed associations.<\/p>\n

Conclusion<\/strong> \u2014 Maternal anemia and relative erythrocytosis were each associated with neonatal morbidity and mortality in a high-income setting. Randomized clinical trials should evaluate the effect of iron therapy on maternal and perinatal outcomes by degree of hemoglobin correction.<\/p>\n","protected":false},"excerpt":{"rendered":"

Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal outcomes in high-income countries is largely unknown. Objective \u2014 To assess early pregnancy hemoglobin concentration and associated severe neonatal morbidity and mortality (SNM-M) in a high-income setting. Design \u2014 Population-based, retrospective cohort study. Setting \u2014 […]<\/p>\n","protected":false},"template":"","migration-helper-automated":[],"migration-manual":[],"topic":[40,26],"migration-helper-qa-sample-set":[],"class_list":["post-23329","journal_article","type-journal_article","status-publish","hentry","topic-cardiovascular-disease","topic-maternity-and-neonatal-care"],"acf":{"citation":"Shams I, Tang GH, Wang X, Walker M, Baxter NN, Gomes T, Ray JG, Sholzberg M. Ann Intern Med<\/em>. 2026; Feb 3 [Epub ahead of print].","source_url":"https:\/\/doi.org\/10.7326\/annals-25-02586","ices_scientist":[1177,1252,1338],"site":[6733],"research_program":[6740],"news_release":"","journal_article":"","atlas":"","research_report":"","infographic":"","video":"","downloads":null,"links":null,"sitecore_item_id":"","sitecore_item_name":"","sitecore_field_values":"","previous_url":""},"yoast_head":"\nICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study<\/title>\n<meta name=\"description\" content=\"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"ICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study\" \/>\n<meta property=\"og:description\" content=\"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/\" \/>\n<meta property=\"og:site_name\" content=\"ICES\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/ICESOntario\/\" \/>\n<meta property=\"article:modified_time\" content=\"2026-02-25T20:45:01+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.ices.on.ca\/wp-content\/uploads\/2024\/11\/ic-es-data-discovery-better-health-logo.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"675\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\\\/\",\"url\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\\\/\",\"name\":\"ICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#website\"},\"datePublished\":\"2026-02-03T20:37:05+00:00\",\"dateModified\":\"2026-02-25T20:45:01+00:00\",\"description\":\"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\\\/#breadcrumb\"},\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Journal Articles\",\"item\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/publications\\\/journal-articles\\\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#website\",\"url\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/\",\"name\":\"ICES\",\"description\":\"POPULATION-BASED HEALTH RESEARCH THAT MAKES A DIFFERENCE\",\"publisher\":{\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#organization\"},\"alternateName\":\"Institute for Clinical Evaluative Sciences\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"fr-FR\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#organization\",\"name\":\"ICES\",\"alternateName\":\"Institute for Clinical Evaluative Sciences\",\"url\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/www.ices.on.ca\\\/wp-content\\\/uploads\\\/2023\\\/04\\\/ices-logo.png\",\"contentUrl\":\"https:\\\/\\\/www.ices.on.ca\\\/wp-content\\\/uploads\\\/2023\\\/04\\\/ices-logo.png\",\"width\":\"676\",\"height\":\"618\",\"caption\":\"ICES\"},\"image\":{\"@id\":\"https:\\\/\\\/www.ices.on.ca\\\/fr\\\/#\\\/schema\\\/logo\\\/image\\\/\"},\"sameAs\":[\"https:\\\/\\\/www.facebook.com\\\/ICESOntario\\\/\",\"https:\\\/\\\/www.linkedin.com\\\/company\\\/ices-research-institute\\\/\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"ICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study","description":"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/","og_locale":"fr_FR","og_type":"article","og_title":"ICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study","og_description":"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal","og_url":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/","og_site_name":"ICES","article_publisher":"https:\/\/www.facebook.com\/ICESOntario\/","article_modified_time":"2026-02-25T20:45:01+00:00","og_image":[{"width":1200,"height":675,"url":"https:\/\/www.ices.on.ca\/wp-content\/uploads\/2024\/11\/ic-es-data-discovery-better-health-logo.jpg","type":"image\/jpeg"}],"twitter_card":"summary_large_image","schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/","url":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/","name":"ICES | Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study","isPartOf":{"@id":"https:\/\/www.ices.on.ca\/fr\/#website"},"datePublished":"2026-02-03T20:37:05+00:00","dateModified":"2026-02-25T20:45:01+00:00","description":"Background \u2014 Anemia affects up to 50% of pregnancies. The relation between early pregnancy maternal hemoglobin concentration and important perinatal","breadcrumb":{"@id":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/#breadcrumb"},"inLanguage":"fr-FR","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/hemoglobin-concentration-in-early-pregnancy-and-severe-neonatal-morbidity-and-mortality\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.ices.on.ca\/fr\/"},{"@type":"ListItem","position":2,"name":"Journal Articles","item":"https:\/\/www.ices.on.ca\/fr\/publications\/journal-articles\/"},{"@type":"ListItem","position":3,"name":"Hemoglobin concentration in early pregnancy and severe neonatal morbidity and mortality: population-based cohort study"}]},{"@type":"WebSite","@id":"https:\/\/www.ices.on.ca\/fr\/#website","url":"https:\/\/www.ices.on.ca\/fr\/","name":"ICES","description":"POPULATION-BASED HEALTH RESEARCH THAT MAKES A DIFFERENCE","publisher":{"@id":"https:\/\/www.ices.on.ca\/fr\/#organization"},"alternateName":"Institute for Clinical Evaluative Sciences","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.ices.on.ca\/fr\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"fr-FR"},{"@type":"Organization","@id":"https:\/\/www.ices.on.ca\/fr\/#organization","name":"ICES","alternateName":"Institute for Clinical Evaluative Sciences","url":"https:\/\/www.ices.on.ca\/fr\/","logo":{"@type":"ImageObject","inLanguage":"fr-FR","@id":"https:\/\/www.ices.on.ca\/fr\/#\/schema\/logo\/image\/","url":"https:\/\/www.ices.on.ca\/wp-content\/uploads\/2023\/04\/ices-logo.png","contentUrl":"https:\/\/www.ices.on.ca\/wp-content\/uploads\/2023\/04\/ices-logo.png","width":"676","height":"618","caption":"ICES"},"image":{"@id":"https:\/\/www.ices.on.ca\/fr\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/ICESOntario\/","https:\/\/www.linkedin.com\/company\/ices-research-institute\/"]}]}},"_links":{"self":[{"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/journal_article\/23329","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/journal_article"}],"about":[{"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/types\/journal_article"}],"acf:post":[{"embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/research_program\/6740"},{"embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/site\/6733"},{"embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/ices_scientist\/1338"},{"embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/ices_scientist\/1252"},{"embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/ices_scientist\/1177"}],"wp:attachment":[{"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/media?parent=23329"}],"wp:term":[{"taxonomy":"migration-helper-automated","embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/migration-helper-automated?post=23329"},{"taxonomy":"migration-manual","embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/migration-manual?post=23329"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/topic?post=23329"},{"taxonomy":"migration-helper-qa-sample-set","embeddable":true,"href":"https:\/\/www.ices.on.ca\/fr\/wp-json\/wp\/v2\/migration-helper-qa-sample-set?post=23329"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}