{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,31]],"date-time":"2025-12-31T00:28:04Z","timestamp":1767140884366,"version":"3.48.0"},"reference-count":46,"publisher":"BMJ","issue":"12","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2025,12,5]]},"published-print":{"date-parts":[[2025,12]]},"abstract":"<jats:p>Neonatal hypocalcaemia (NH) is a common metabolic disorder, particularly in preterm and high-risk infants. It may be life-threatening, with a broad spectrum of clinical manifestations, although early-onset cases can remain clinically silent.<\/jats:p>\n                  <jats:p>We describe a premature infant with refractory early-onset NH, secondary to severe maternal vitamin D deficiency. Despite an initial asymptomatic presentation, the infant developed persistent biochemical abnormalities requiring supplementation with calcium, magnesium and high-dose vitamin D. Maternal evaluation confirmed marked vitamin D deficiency with secondary hyperparathyroidism, highlighting the direct impact of maternal status on neonatal calcium homeostasis.<\/jats:p>\n                  <jats:p>This case illustrates how neonatal vitamin D levels depend almost entirely on maternal stores during pregnancy, making maternal hypovitaminosis D a key and preventable risk factor for NH. It also emphasises the underestimated prevalence of vitamin D deficiency among pregnant women worldwide, especially in vulnerable populations. Early recognition and intervention are therefore essential to prevent complications in both mother and child.<\/jats:p>","DOI":"10.1136\/bcr-2025-270711","type":"journal-article","created":{"date-parts":[[2025,12,30]],"date-time":"2025-12-30T18:05:13Z","timestamp":1767117913000},"page":"e270711","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Neonatal hypocalcaemia due to maternal vitamin D deficiency: a preventable and underestimated condition"],"prefix":"10.1136","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-5561-0013","authenticated-orcid":false,"given":"Madalena","family":"Ferreira","sequence":"first","affiliation":[{"name":"Children\u2019s Department, Hospital de Cascais Dr Jos\u00e9 de Almeida, Alcabideche, Lisbon, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0977-5596","authenticated-orcid":false,"given":"Maria","family":"Limbert","sequence":"additional","affiliation":[{"name":"Children\u2019s Department, Hospital de Cascais Dr Jos\u00e9 de Almeida, Alcabideche, Lisbon, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sofia","family":"Deuchande","sequence":"additional","affiliation":[{"name":"Children\u2019s Department, Hospital de Cascais Dr Jos\u00e9 de Almeida, Alcabideche, Lisbon, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cristina","family":"Novais","sequence":"additional","affiliation":[{"name":"Children\u2019s Department, Hospital de Cascais Dr Jos\u00e9 de Almeida, Alcabideche, Lisbon, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2025,12,30]]},"reference":[{"key":"2025123016251304000_18.12.e270711.1","doi-asserted-by":"crossref","first-page":"190","DOI":"10.5005\/jp-journals-11002-0017","article-title":"Approach to Neonatal Hypocalcemia","volume":"1","author":"Pillai","year":"2022","journal-title":"Newborn"},{"key":"2025123016251304000_18.12.e270711.2","doi-asserted-by":"crossref","DOI":"10.1155\/2019\/4318075","article-title":"Clinical Approach to Hypocalcemia in Newborn Period and Infancy: Who Should Be Treated?","volume":"2019","author":"Vuralli","year":"2019","journal-title":"Int J Pediatr"},{"key":"2025123016251304000_18.12.e270711.3","doi-asserted-by":"crossref","unstructured":"Root AW , Levine MA . 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