Twin birth rates and obstetric interventions in Iceland : A nationwide study from 1997 to 2018

• Published in: International Journal of Gynecology & Obstetrics
• Main Authors: Ontiveros, Jamie Lynn, Gunnarsdóttir, Jóhanna, Guðnadóttir, Sigurbjörg Anna, Aspelund, Thor, Einarsdóttir, Kristjana
• Other Authors: Interdisciplinary Graduate Studies, Faculty of Medicine, Other departments, University of Iceland
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Fæðinga- og kvensjúkdómafræði; assisted reproduction; cesarean; delivery; induction of labor; twin pregnancy; Parturition; Humans; Pregnancy; Twin; Cesarean Section; Labor; Obstetric; Female; Birth Rate; Iceland/epidemiology; Retrospective Studies; Obstetrics and Gynecology; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/4202; https://doi.org/10.1002/ijgo.14817

Funding Information: We thank the Icelandic Directorate of Health for providing the data. Publisher Copyright: © 2023 The Authors. International Journal of Gynecology & Obstetrics published by John Wiley & Sons Ltd on behalf of International Federation of Gynecology and Obstetrics. OBJECTIVE: Twin pregnancies are associated with increased antepartum and intrapartum risks. Limited multiple embryo transfers are associated with decreased twin birth rates. We aimed to study the effect of 2009 Icelandic regulations on twin birth rates and examine obstetric intervention rates for twin births during the study period. METHODS: The study included all births (N = 94 028) in Iceland during 1997-2018. Twin birth rates and obstetric intervention rates were compared over birth year periods using modified Poisson regression adjusted for confounders. RESULTS: An observed decrease in the twin birth rate trend was most notable from 2006 until 2009. Twin birth decreased in 2009-2013 (prevalence ratio [PR] 0.74, 95% confidence interval [CI] 0.64-0.86) and in 2014-2018 (PR 0.74, 95% CI 0.64-0.86) compared with 1997-2002. This decrease was only evident for women aged 30+ years in stratified analysis. Induction of labor rates increased from 26% in 1997-2002 to 44% in 2014-2018 (adjusted rate ratio [ARR] 2.10, 95% CI 1.72-2.57) whereas elective cesarean section (ARR 0.80, 95% CI 0.59-1.07) and urgent cesarean section (ARR 0.79, 95% CI 0.63-1.00) rates appeared to decline. CONCLUSION: Twin births decreased during the study period. International guidelines published before the Icelandic regulations may have affected twin birth rates in Iceland. Induction of labor rates for twins increased while cesarean section rates decreased. Peer reviewed