{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T06:56:08Z","timestamp":1774940168796,"version":"3.50.1"},"reference-count":8,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2011,1,11]],"date-time":"2011-01-11T00:00:00Z","timestamp":1294704000000},"content-version":"vor","delay-in-days":10237,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Obstet Gynecol Scand"],"published-print":{"date-parts":[[1983,1]]},"abstract":"<jats:p><jats:bold>Abstract. <\/jats:bold> The incidence of birth has been determined for each hour of the day for all births in Norway in 1968\u20131977 of fetuses of 16 weeks of gestation or older, with resident mothers. The 24\u2010hour incidence variations of births (A) with spontaneous onset and parturition, (B) with spontaneous onset, but delivery intervention, (C) with induced onset, but spontaneous birth, and (D) with induced onset and delivery intervention, are all different.<\/jats:p><jats:p>It is shown that the curve for the hourly incidence of birth category A coincides very well with previous results of other workers. When multiple births are excluded and category A is split into first and later births in Northern and Southern Norway, dissimilarities arise between the respective 24\u2010hour incidence curves.<\/jats:p><jats:p>The results indicate that the 24\u2010hour birth incidence variation has an underlying endogenous, circadian rhythmicity \u2010possibly synchronized by the sun.<\/jats:p><jats:p>The 24\u2010hour rhythmicities of birth categories B, C and D seem to be purely exogenous \u2010 reflecting the working activity rhythms of hospital obstetricians and midwives.<\/jats:p>","DOI":"10.3109\/00016348309155754","type":"journal-article","created":{"date-parts":[[2009,12,8]],"date-time":"2009-12-08T18:00:44Z","timestamp":1260295244000},"page":"31-36","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":41,"title":["The 24\u2010Hour Rhythmicity of birth"],"prefix":"10.1111","volume":"62","author":[{"given":"Eystein","family":"Glattre","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tor","family":"Bjerkedal","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2011,1,11]]},"reference":[{"key":"e_1_2_1_2_1","first-page":"442","volume-title":"Varighet av spontant inntredende f\u00f6dsel","author":"Bakketeig L. S.","year":"1977"},{"key":"e_1_2_1_3_1","first-page":"7","volume-title":"Medical Registration of Births in Norway during the 5\u2010Year Period 1967\u20131971","author":"Bjerkedal T.","year":"1975"},{"key":"e_1_2_1_4_1","first-page":"7","volume-title":"The Physiological Clock","author":"Banning E.","year":"1973"},{"key":"e_1_2_1_5_1","first-page":"43","article-title":"The Hour of Birth, Birt, J. prev. soc.","volume":"7","author":"Charles E.","year":"1953","journal-title":"Med."},{"key":"e_1_2_1_6_1","first-page":"112","volume-title":"Human Orcadian Rhythms","author":"Conroy R. T. W. L.","year":"1970"},{"key":"e_1_2_1_7_1","first-page":"229","article-title":"Note sur le rythme journalier du debut des douleurs de l'accouchement","volume":"66","author":"Gauquelin M.","year":"1967","journal-title":"Gynecol Obstet"},{"key":"e_1_2_1_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1749-6632.1962.tb30618.x"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9378(60)90382-3"}],"container-title":["Acta Obstetricia et Gynecologica Scandinavica"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.3109%2F00016348309155754","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.3109\/00016348309155754","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,19]],"date-time":"2023-10-19T06:27:01Z","timestamp":1697696821000},"score":1,"resource":{"primary":{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/10.3109\/00016348309155754"}},"subtitle":["A Populational Study"],"short-title":[],"issued":{"date-parts":[[1983,1]]},"references-count":8,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1983,1]]}},"alternative-id":["10.3109\/00016348309155754"],"URL":"https:\/\/doi.org\/10.3109\/00016348309155754","archive":["Portico"],"relation":{},"ISSN":["0001-6349","1600-0412"],"issn-type":[{"value":"0001-6349","type":"print"},{"value":"1600-0412","type":"electronic"}],"subject":[],"published":{"date-parts":[[1983,1]]},"assertion":[{"value":"2011-01-11","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}