Risk of obstetric anal sphincter injury associated with female genital mutilation/cutting and timing of deinfibulation

Abstract

Introduction: A greater risk of obstetric anal sphincter injury has been reported among African migrants in several host countries compared with the general population. To what degree female genital mutilation/cutting affects this risk is not clear. In infibulated women, deinfibulation prevents anal sphincter injury. Whether the timing of deinfibulation affects the risk, is unknown. This study aimed to investigate the risks of anal sphincter injury associated with female genital mutilation/cutting and timing of deinfibulation in Norway, and to compare the rates of anal sphincter injury in Somali-born women and the general population.

Material and methods: In a historical cohort study, nulliparous Somali-born women who had a vaginal birth in the period 1990-2014 were identified by the Medical Birth Registry of Norway and data collected from medical records. Exposures were female genital mutilation/cutting status and deinfibulation before labor, during labor or no deinfibulation. The main outcome was obstetric anal sphincter injuries.

Results: Rates of obstetric anal sphincter injury did not differ significantly by female genital mutilation/cutting status (type 1-2: 10.2%, type 3: 11.3%, none: 15.2% P = 0.17). The total rate of anal sphincter injury was 10.3% compared to 5.0% among nulliparous women in the general Norwegian population. Women who underwent deinfibulation during labor had a lower risk than women who underwent deinfibulation before labor (odds ratio 0.48, 95% confidence interval 0.27-0.86, P = 0.01).

Conclusions: The high rate of anal sphincter injury in Somali nulliparous women was not related to type of female genital mutilation/cutting. Deinfibulation during labor protected against anal sphincter injury, whereas deinfibulation before labor was associated with a doubled risk. Deinfibulation before labor should not be routinely recommended during pregnancy.

Keywords: Somalia; country of birth; female genital mutilation/cutting; migration; nulliparity; obstetric anal sphincter injury; timing of deinfibulation.

FIGURE 1

Classification of female genital mutilation/cutting.

FIGURE 2

Flowchart of participants. The original cohort of nulliparous Somali‐born women 1990–2014 and the subset of women with vaginal births (blue). Aggregated data from the medical Birth Registry of Norway for all nulliparous women with a vaginal birth (gray box).

FIGURE 3

Type 3 female genital mutilation/cutting, deinfibulation before labor and obstetric anal sphincter injury by delivery year in nulliparous Somali‐born women with vaginal birth in 1990–2014.

FIGURE 4

Obstetric anal sphincter injury, instrumental vaginal birth, episiotomy and blood loss in nulliparous Somali‐born women in South East Norway and women in the general population with vaginal birth in 1990–2014.