To Örebro University

Pelvic floor dysfunction (PFD), including urinary incontinence, faecal incontinence (FI), and pelvic organ prolapse, is highly prevalent among parous women. There is evidence that pregnancy, vaginal delivery, and obstetric perineal tears increase the risk of pelvic floor dysfunction, but many of the studies in this field are retrospective. The overall aim of this thesis was to prospectively examine risk factors for perineal and vaginal tears and postpartum PFD in primiparous women.

Study I was a validation study of a protocol for documentation of perineal tears, including 187 primiparous women in 2015–2016. The coverage of documentation was higher in the protocol compared to the obstetric record system (ObstetriX). Incidence of second degree perineal tears was 26% according to the protocol and 11% according to ObstetriX.

Studies II–IV utilized a cohort of initially nulliparous women (n=1049) prospectively included in early pregnancy in 2014–2017. Women completed questionnaires on PFD in early and late pregnancy and at 8 weeks and 1 year postpartum.

Study II (n=644) showed that high foetal weight and vacuum extraction were risk factors for both second degree tears and OASI, suggesting that these tears should be viewed as a continuum rather than different entities. Risk factors for high vaginal tears were large foetal head circumference, vacuum extraction, and heredity of PFD/connective tissue deficiency. 

Study III (n=670) found that vaginal delivery increased the risk of stress urinary incontinence (SUI) but not urgency urinary incontinence (UUI) 1 year postpartum. No single characteristic of the vaginal delivery was associated with SUI. SUI during pregnancy increased the risk of SUI postpartum, and UUI during pregnancy increased the risk of UUI postpartum.

Study IV (n=898) showed that FI increased by late pregnancy, and that this increase persisted 1 year postpartum. Obstructed defecation was associated with increased FI postpartum, suggesting that post-defecatory faecal loss may be an underlying mechanism of FI. 

Overall conclusion: The extent to which pregnancy, vaginal delivery, and their respective characteristics contributed to the development of PFD differed between the pelvic floor disorders studied. For SUI, both the pregnancy and the vaginal delivery increased the risk, whereas for FI it was the pregnancy itself rather than the vaginal delivery that was demonstrated to increase the risk.