{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T23:37:28Z","timestamp":1785800248794,"version":"3.56.0"},"reference-count":23,"publisher":"Wiley","issue":"10","license":[{"start":{"date-parts":[[2015,3,11]],"date-time":"2015-03-11T00:00:00Z","timestamp":1426032000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["BJOG"],"published-print":{"date-parts":[[2015,9]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>To investigate pregnancy and perinatal outcomes in twin births among women with and without polycystic ovary syndrome (<jats:styled-content style=\"fixed-case\">PCOS<\/jats:styled-content>) diagnosis.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Population\u2010based cohort study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>Sweden.<\/jats:p><\/jats:sec><jats:sec><jats:title>Population<\/jats:title><jats:p>We identified 20\u00a0965 women with twin births between 1995 and 2009 of whom 226 had a <jats:styled-content style=\"fixed-case\">PCOS<\/jats:styled-content> diagnosis through linkage between the Swedish Medical Birth Register and the Swedish National Patient Register.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Calculating risk ratios (<jats:styled-content style=\"fixed-case\">RR<\/jats:styled-content>) with 95% confidence intervals (<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>) using a log\u2010binomial regression model and hazard ratios (<jats:styled-content style=\"fixed-case\">HR<\/jats:styled-content>) with 95% CI for preterm birth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main outcome measures<\/jats:title><jats:p>Preterm birth, low birthweight, caesarean section, pre\u2010eclampsia, Apgar score &lt;7 at 5\u00a0minutes and perinatal mortality.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p><jats:styled-content style=\"fixed-case\">PCOS<\/jats:styled-content> diagnosis in twin pregnancy was associated with increased risk of preterm delivery (51% versus 43%, <jats:styled-content style=\"fixed-case\">RR<\/jats:styled-content> 1.18 [95% CI 1.03\u20131.37]), particularly spontaneous preterm delivery (37% versus 28%; <jats:styled-content style=\"fixed-case\">RR<\/jats:styled-content> 1.30 [95% CI 1.09\u20131.55]) and very preterm birth (&lt;32\u00a0weeks) (14% versus 8%, <jats:styled-content style=\"fixed-case\">RR<\/jats:styled-content> 1.62 [95% CI 1.10\u20132.37]). Twins of <jats:styled-content style=\"fixed-case\">PCOS<\/jats:styled-content> mothers had more often low birthweight (48% versus 39%, adjusted <jats:styled-content style=\"fixed-case\">RR<\/jats:styled-content> 1.40 [95% CI 1.09\u20131.80]). This difference disappeared when adjusting for gestational age. No risk difference was found for caesarean section, pre\u2010eclampsia, low 5\u2010minute Apgar score or perinatal mortality.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>The risk of preterm delivery in twin pregnancies is increased by having a <jats:styled-content style=\"fixed-case\">PCOS<\/jats:styled-content> diagnosis. This should be considered in risk estimation and antenatal follow\u2010up of twin pregnancies.<\/jats:p><\/jats:sec>","DOI":"10.1111\/1471-0528.13339","type":"journal-article","created":{"date-parts":[[2015,3,12]],"date-time":"2015-03-12T01:57:19Z","timestamp":1426125439000},"page":"1295-1302","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":34,"title":["Pregnancy and perinatal outcomes in women with polycystic ovary syndrome and twin births: a population\u2010based cohort study"],"prefix":"10.1111","volume":"122","author":[{"given":"TS","family":"L\u00f8vvik","sequence":"first","affiliation":[{"name":"Institute of Laboratory Medicine Children's and Women's Health Norwegian University of Science and Technology Trondheim Norway"},{"name":"Department of Obstetrics and Gynaecology St Olavs Hospital Trondheim Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A\u2010K","family":"Wikstr\u00f6m","sequence":"additional","affiliation":[{"name":"Department of Medicine Solna Clinical Epidemiology Unit Karolinska Institute Stockholm Sweden"},{"name":"Department of Women's and Children's Health Uppsala University Uppsala Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M","family":"Neovius","sequence":"additional","affiliation":[{"name":"Department of Medicine Solna Clinical Epidemiology Unit Karolinska Institute Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"O","family":"Stephansson","sequence":"additional","affiliation":[{"name":"Department of Medicine Solna Clinical Epidemiology Unit Karolinska Institute Stockholm Sweden"},{"name":"Division of Obstetrics and Gynaecology Department of Women's and Children's Health Karolinska Institute Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"N","family":"Roos","sequence":"additional","affiliation":[{"name":"Department of Medicine Solna Clinical Epidemiology Unit Karolinska Institute Stockholm Sweden"},{"name":"Division of Obstetrics and Gynaecology Department of Women's and Children's Health Karolinska Institute Stockholm Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E","family":"Vanky","sequence":"additional","affiliation":[{"name":"Institute of Laboratory Medicine Children's and Women's Health Norwegian University of Science and Technology Trondheim Norway"},{"name":"Department of Obstetrics and Gynaecology St Olavs Hospital Trondheim Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2015,3,11]]},"reference":[{"key":"e_1_2_6_2_1","doi-asserted-by":"publisher","DOI":"10.1210\/jc.85.7.2434"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2006.01008.x"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/deh098"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.d6309"},{"issue":"4","key":"e_1_2_6_6_1","first-page":"CD002249","article-title":"Clomiphene and anti\u2010oestrogens for ovulation induction in PCOS","author":"Brown J","year":"2009","journal-title":"Cochrane Database Syst Rev"},{"key":"e_1_2_6_7_1","doi-asserted-by":"publisher","DOI":"10.1093\/humupd\/dml036"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1038\/jp.2011.194"},{"key":"e_1_2_6_9_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2011.03206.x"},{"key":"e_1_2_6_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.siny.2010.08.001"},{"key":"e_1_2_6_11_1","doi-asserted-by":"publisher","DOI":"10.1007\/s10654-009-9350-y"},{"key":"e_1_2_6_12_1","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2458-11-450"},{"key":"e_1_2_6_13_1","doi-asserted-by":"publisher","DOI":"10.1177\/140349489001800209"},{"key":"e_1_2_6_14_1","doi-asserted-by":"publisher","DOI":"10.1034\/j.1600-0412.2003.00112.x"},{"key":"e_1_2_6_15_1","doi-asserted-by":"publisher","DOI":"10.3109\/00016349709034900"},{"key":"e_1_2_6_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(10)62187-3"},{"key":"e_1_2_6_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2011.03.021"},{"key":"e_1_2_6_18_1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2013.6295"},{"key":"e_1_2_6_19_1","doi-asserted-by":"publisher","DOI":"10.1080\/09513590801893398"},{"key":"e_1_2_6_20_1","doi-asserted-by":"publisher","DOI":"10.1111\/1471-0528.12558"},{"key":"e_1_2_6_21_1","doi-asserted-by":"publisher","DOI":"10.1375\/1369052022848"},{"key":"e_1_2_6_22_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(08)61041-7"},{"key":"e_1_2_6_23_1","doi-asserted-by":"publisher","DOI":"10.1186\/1477-7827-9-39"},{"key":"e_1_2_6_24_1","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/dep399"}],"container-title":["BJOG: An International Journal of Obstetrics &amp; 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