{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T03:23:42Z","timestamp":1772767422066,"version":"3.50.1"},"reference-count":8,"publisher":"BMJ","issue":"7325","license":[{"start":{"date-parts":[[2001,12,8]],"date-time":"2001-12-08T00:00:00Z","timestamp":1007769600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/www.bmj.com\/company\/legal-information\/terms-conditions\/legal-information\/tdm-licencepolicy"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["BMJ"],"accepted":{"date-parts":[[2001,8,29]]},"published-print":{"date-parts":[[2001,12,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    <jats:bold>Objective:<\/jats:bold>\n                    To assess the impact of time of birth on infant mortality and early neonatal mortality in full term and preterm births.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Design:<\/jats:bold>\n                    Analysis of data from the Swedish birth register, 1973-95.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Participants:<\/jats:bold>\n                    2 102 324 spontaneous live births of infants without congenital malformation.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Outcome measurements:<\/jats:bold>\n                    Absolute and relative risk of infant mortality, early neonatal mortality, and early neonatal mortality related to asphyxia.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Results:<\/jats:bold>\n                    Infant mortality, early neonatal mortality, and early neonatal mortality related to asphyxia were higher in infants who were born during the night (9 pm to 9 am) compared with those born during the day for 1973-9, 1980-9, and 1990-5. The difference was more dramatic for preterm infants. The largest difference was observed during 1990-5, when there was a 30% increase in early neonatal mortality (relative risk 1.31, 95% confidence interval 1.10 to 1.57) and a 70% increase in early neonatal mortality related to asphyxia (1.70, 1.22 to 2.38) in preterm infants born during the night compared with rates for preterm infants born during the day. A detailed analysis over 24 hours revealed two \u201chigh risk\u201d periods: between 5 pm and 1 am and around 9 am.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Conclusions:<\/jats:bold>\n                    Infants born during the night have a greater risk of infant and early neonatal mortality and early neonatal mortality related to asphyxia than those born during the day. There has been no improvement over the past two decades. The problem is more serious for preterm births and was even worse in the 1990s. Shift changes and the hours immediately after such changes are high risk periods for neonatal care.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:boxed-text position=\"float\">\n                      <jats:sec>\n                        <jats:title>What is already known on this topic<\/jats:title>\n                        <jats:p>Infants born at night have a greater risk of early neonatal mortality and early neonatal mortality related to asphyxia than those born during the day<\/jats:p>\n                        <jats:p>The causes are unclear but may be related to insufficient or less experienced staff or excess workload during the night<\/jats:p>\n                      <\/jats:sec>\n                      <jats:sec>\n                        <jats:title>What this study adds<\/jats:title>\n                        <jats:p>In Sweden the relative risks of infant and early neonatal mortality and mortality related to asphyxia for infants born during the night compared with during the day did not diminish during 1973-95, are greater for preterm infants, and were greater in the 1990s<\/jats:p>\n                        <jats:p>There are two \u201chigh risk\u201d periods for early neonatal mortality: 5 pm to 1 am and around 9 am<\/jats:p>\n                        <jats:p>The exact reasons are unclear but better vigilance and an improvement in shift changes may be required to improve neonatal health care further<\/jats:p>\n                      <\/jats:sec>\n                    <\/jats:boxed-text>\n                  <\/jats:p>","DOI":"10.1136\/bmj.323.7325.1327","type":"journal-article","created":{"date-parts":[[2002,7,27]],"date-time":"2002-07-27T06:32:19Z","timestamp":1027751539000},"page":"1327","source":"Crossref","is-referenced-by-count":64,"title":["Timing of birth and infant and early neonatal mortality in Sweden 1973-95: longitudinal birth register study"],"prefix":"10.1136","volume":"323","author":[{"given":"Z C","family":"Luo","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J","family":"Karlberg","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2001,12,8]]},"reference":[{"key":"2025122111231174000_323.7325.1327.1","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.321.7256.274"},{"key":"2025122111231174000_323.7325.1327.2","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.316.7132.657"},{"key":"2025122111231174000_323.7325.1327.3","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.317.7157.539"},{"key":"2025122111231174000_323.7325.1327.4","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1177\/140349489001800209","article-title":"A quality study of a medical birth registry.","volume":"18","author":"Cnattingius","year":"1990","journal-title":"Scan J Soc Med"},{"key":"2025122111231174000_323.7325.1327.5","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/152.12.1107"},{"key":"2025122111231174000_323.7325.1327.6","doi-asserted-by":"publisher","DOI":"10.1002\/sim.858"},{"key":"2025122111231174000_323.7325.1327.7","doi-asserted-by":"publisher","DOI":"10.1001\/jama.284.7.843"},{"key":"2025122111231174000_323.7325.1327.8","unstructured":"Pan American Health Organization .II. Health by population group. In:Health in the Americas. Washington, DC: PAHO Scientific Publication,1998."}],"container-title":["BMJ"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/data.bmj.org\/tdm\/10.1136\/bmj.323.7325.1327","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bmj.323.7325.1327","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,21]],"date-time":"2025-12-21T19:23:17Z","timestamp":1766344997000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.bmj.com\/lookup\/doi\/10.1136\/bmj.323.7325.1327"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2001,12,8]]},"references-count":8,"journal-issue":{"issue":"7325","published-online":{"date-parts":[[2001,12,8]]},"published-print":{"date-parts":[[2001,12,8]]}},"alternative-id":["10.1136\/bmj.323.7325.1327"],"URL":"https:\/\/doi.org\/10.1136\/bmj.323.7325.1327","relation":{},"ISSN":["0959-8138","1468-5833"],"issn-type":[{"value":"0959-8138","type":"print"},{"value":"1468-5833","type":"electronic"}],"subject":[],"published":{"date-parts":[[2001,12,8]]}}}