Association between maternal region of origin and birth and obstetric anal sphincter injury, by length of residence: A nationwide cohort study

Introduction: Obstetric anal sphincter injury (OASI) is a severe obstetric complication, associated with long-term urogenital pain and dysfunction. Few studies have explored association between migration related characteristics and OASI. Our aim was to examine the association between maternal region of origin and birth, and OASI, by length of residence in Norway and paternal birthplace. Methods: This is a population-based cohort study on data from the Medical Birth Registry of Norway, including all primiparous women with a vaginal livebirth of a singleton cephalic foetus between 2008 and 2017 (n=188 658).