BACKGROUND:
A previous cesarean may influence the risk of tears in the genital tract during the a following birth.

OBJECTIVES:
The objective of this study was to describe the incidence of sphincter injuries (OASI) in a low-risk population of women, who planned to give birth at home or in freestanding midwifery units in Germany and to compare the prevalence of OASI in primiparae vs. multiparae with a previous cesarean (VBAC).

METHODS:
A population-based retrospective cohort study of planned out of hospital births in Germany between 2016 and 2022. Included were low risk women with a planned second birth after primary and secondary cesarean and low risk first time mothers.

RESULTS:
105,000 birth data records from 2016-2022 were analysed. All had planned to give birth at home or in a freestanding midwife-led unit. The incidence of OASI is below the clinical level due to the low-risk population. This applies both to women giving birth for the first time and to women in post-cesarean status compared to similar international studies. The incidence of sphincter injury in the subsequent birth in the status post primary caesarean is 35% and post secondary caesarean 54% higher than in low risk first time mothers. The often common clinical interventions can be ruled out as the only justification due to the out of hospital setting.

CONCLUSIONS:
The incidence of OASI in low-risk VBAC women differs according to the time of the cesarean and also from first-time mothers. In both groups OASI were below the overall clinical population. The chance of a out of hospital birth without a OASI is 97%, even in VBAC

KEY MESSAGE:
VBAC is an independent risk factor for OASI, even in low-risk birthing women. If the women are informed about the risk with regard to OASI, the status after caesarean need not be a reason to avoid an out-of-hospital birth. Poster session 2 (Group A)