Pirhonen JP, Grenman SE, Haadem K, Gudmundsson S, Lindqvist P, Siihola S, Erkkola RU, Marsal K. Frequency of anal sphincter rupture at delivery in Sweden and Finland - result of difference in manual help to the baby's head. Acta Obstet Gynecol Scand 77:974-77, 1998
 

Laine K, Pirhonen T, Rolland R, Pirhonen J. Decreasing the incidence of anal sphincter tears during pregnancy. Obstet Gynecol 111:1053-57, 2008
 

Laine K, Gissler M, Pirhonen J. Changing incidence of anal sphincter tears in four Nordic countries through the last decades. Eur J Obstet Gynecol Reprod Biol 146:71-75, 2009
 

Hals E, Øian P, Pirhonen T, Gissler M, Hjelle S, Nilsen EB, Severinsen AM, Solsletten E, Hartgill T, Pirhonen J. A Multicenter Interventional Program to Reduce the Incidence of Anal Sphincter Tears. Obstet Gynecol 116;901-8, 2010
 

Pirhonen T, Gissler M, Hartgill T, Pirhonen J. Experiences of expert midwives in a training program aimed at decreasing perineal tears. Int J Nursing & Midwifery 3(6):70-75, 2011
 

Stedenfeldt M, Pirhonen J, Blix E, Wilsgaard T, Vonen B, Øian P. Episiotomy characteristics and risk for obstetric anal sphincter injuries: a case-control study. BJOG 119:724-30, 2012
 

Stedenfeldt M, Øian P, Gissler M, Blix E, Pirhonen J. Risk factors for obstetric anal sphincter injury after a successful multicentre interventional programme. BJOG 121:83-91, 2014

Stedenfeldt M, Pirhonen J, Blix E, Wilsdaard T, Vonen B, Øian P. Anal incontinence, urinary incontinence and sexual problems in primiparous women: a comparison between women with episiotomy only and women with episiotomy  and obstetric anal sphincter injury. BMC Women’s Health 12/2014: 157

Leenskjold S, Höj L, Pirhonen J. Manual protection of the perineum reduces the risk of obstetric anal sphincter ruptures. Dan Med J 62(5): A5075, 2015

Pirhonen J. Preventing anal sphincter tears during delivery. A review. EC Gynaecology 2.2: 163-9, 2015

Pirhonen T, Gissler M, Hals E, Rygh A, Roste R, Hjelle S, Pirhonen J. Birth attendants' own analyses of causes for anal sphincter tears. EC Gynaecology 3.6: 404-10, 2017