{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T18:58:09Z","timestamp":1766516289834},"reference-count":15,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2011,1,7]],"date-time":"2011-01-07T00:00:00Z","timestamp":1294358400000},"content-version":"vor","delay-in-days":6490,"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":[[1993,4]]},"abstract":"<jats:p><jats:italic>Study objective<\/jats:italic>: To analyze risk factors for multiple births.<\/jats:p><jats:p><jats:italic>Design<\/jats:italic>: A case\u2010control study. Cases were 103 women (median age 31 years, range 20\u201044) who delivered multiple births not related with treatment for infertility at the \u2018Clinica Luigi Mangiagalli\u2019 of Milan. A total of 27 women delivered monozygotic twins and 76 dizygotic ones. Controls were 308 women (median age 30, range 17\u201045) admitted for normal delivery on selected days to the same clinic where cases had been identified.<\/jats:p><jats:p><jats:italic>Results<\/jats:italic>: Cases tended to be less educated than controls and the relative risk of multiple pregnancy, compared with women reporting seven years of schooling or less, was 0.4 in those reporting 7\u201011 and 12 or more years of education. When the analysis was done separately for dizygotic and monozygotic multiple pregnancies, this relationship was restricted to dizygotic multiple pregnancies (\u03c7<jats:sup>2<\/jats:sup><jats:sub>1<\/jats:sub> trend for dizygotic pregnancies=3.82, <jats:italic>p<\/jats:italic> = 0.05). A family history of multiple pregnancies was reported in 36 women (48%) with dizygotic multiple pregnancy and 13 (52%) monozygotic ones and 88 (30%) controls. The corresponding relative risks (RR) were 2.2 and 2.5 respectively for dizygotic and monozygotic pregnancies. Compared with nulliparae, the estimated RR of dizygotic multiple pregnancies was 0.5 in women reporting two or more births, but the trend in risk with number of births was not statistically significant. No relationship emerged with spontaneous or induced abortions, body mass index, oral contraceptive or IUD use, age at menarche and risk of multiple pregnancies. <jats:italic>Conclusions<\/jats:italic>: This study confirms the role of familiarity in the risk of multiple pregnancies and suggests some different epidemiological characteristics in dizygotic and monozygotic multiple pregnancies.<\/jats:p>","DOI":"10.3109\/00016349309013368","type":"journal-article","created":{"date-parts":[[2007,11,13]],"date-time":"2007-11-13T19:10:05Z","timestamp":1194981005000},"page":"177-180","update-policy":"http:\/\/dx.doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Risk factors for multiple births"],"prefix":"10.1111","volume":"72","author":[{"given":"Fabio","family":"Parazzini","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luca","family":"Tozzi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Monica","family":"Ferraroni","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luca","family":"Bocciolone","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elena","family":"Molteni","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cristina","family":"Moreschi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luigi","family":"Fedele","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2011,1,7]]},"reference":[{"key":"e_1_2_1_2_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.1991.tb10366.x"},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(83)91463-0"},{"key":"e_1_2_1_4_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.295.6597.510"},{"key":"e_1_2_1_5_1","unstructured":"Paris Conference 1971. Standardization in human cytogenetics.1971.The National Foundation New York1972 Birth Defects: Orig. Art. Ser. 8(7)."},{"key":"e_1_2_1_6_1","first-page":"719","article-title":"Statistical aspects of the analysis of data from retrospective studies of disease","volume":"22","author":"Mantel N.","year":"1959","journal-title":"J Natl Cancer Inst"},{"key":"e_1_2_1_7_1","first-page":"35","volume-title":"Twin Research. Part B: Biology and Epidemiology","author":"Nylander P PS","year":"1978"},{"key":"e_1_2_1_8_1","first-page":"385","article-title":"Twinning in relation to the marital status of the mother","volume":"17","author":"Eriksson A W.","year":"1967","journal-title":"Acta Genet Stat Med"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1136\/adc.64.2.272"},{"key":"e_1_2_1_10_1","doi-asserted-by":"publisher","DOI":"10.1038\/304626a0"},{"key":"e_1_2_1_11_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM196411052711908"},{"key":"e_1_2_1_12_1","first-page":"95","volume-title":"Twin Research 3, Part A: Twin Biology and Multiple Pregnancy","author":"Wyshak G.","year":"1981"},{"key":"e_1_2_1_13_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM197709012970903"},{"key":"e_1_2_1_14_1","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1016\/0002-9378(79)90066-8","article-title":"Oral contraception and twinning: An epidemiologic study","volume":"133","author":"Bracken M B.","year":"1979","journal-title":"Am J Obstet Gynecol"},{"key":"e_1_2_1_15_1","first-page":"105","article-title":"A study of the influence of ovulation stimulants and oral contraception on twin births in England","volume":"34","author":"Webster F.","year":"1985","journal-title":"Acta Genet Med Gemellol"},{"key":"e_1_2_1_16_1","first-page":"91","article-title":"Analyses des variations g\u00e9o\u2010graphiques de la fr\u00e9quence des accouchements g\u00e9mellaires en France. Une approche indirecte de \u013e\u00e9tude des avortements spontan\u00e9s","volume":"27","author":"Hemon D.","year":"1979","journal-title":"Rev Epid\u00e9miol Sant\u00e9 Publique"}],"container-title":["Acta Obstetricia et Gynecologica Scandinavica"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.3109%2F00016349309013368","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.3109\/00016349309013368","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,24]],"date-time":"2023-10-24T18:33:43Z","timestamp":1698172423000},"score":1,"resource":{"primary":{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/10.3109\/00016349309013368"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,4]]},"references-count":15,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1993,4]]}},"alternative-id":["10.3109\/00016349309013368"],"URL":"https:\/\/doi.org\/10.3109\/00016349309013368","archive":["Portico"],"relation":{},"ISSN":["0001-6349","1600-0412"],"issn-type":[{"value":"0001-6349","type":"print"},{"value":"1600-0412","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,4]]},"assertion":[{"value":"2011-01-07","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}