High birth weight is the main risk factor for birth injuries in the anal muscles of the person born, according to a study at the University of Gothenburg. This new method of predicting risks could improve care and reduce injuries.
Five percent of women who give birth to their first child in Sweden maintain birth injuries in the form of Obstetrician injuries to the anal sphincter (OASI), which affect the muscles responsible for controlling gas and bowel movements. These injuries can lead to long -term problems and affect physical health as well as quality of life.
The purpose of this study, published in the Journal of Clinical Epidemiology, was to develop and validate a prediction model that provides an OASI risk assessment before a vaginal tradition.
The study is based on a registry data of all 45 maternity units in Sweden for the 2009 to 2017 period. In total, about 600,000 singleton, Head-Births, the most common form of delivery were examined.
Older babies increased the risk more
The prediction models were designed for three common delivery scenarios: the first vaginal tradition, the vaginal birth after a caesarean section and the second vaginal tradition. Includes a wide range of risk factors, such as baby birth weight, assisted birth with, for example, a vacuum cup, height and age of the person born and the previous Oasi.
The baby’s birth weight was found to be OASI’s strongest predictor in all delivery scenarios – older babies increased the risk of severe vaginal tears. Among those born in their second child vaginal, the previous Oasi was a powerful indicator of a repeated injury. A third risk factor was the use of a vacuum cup.
The prediction model for those born for the second time was accurate, followed by the models for the first time vaginal birth and vaginal birth after a caesarean section. However, the reliability of all three models was equivalent to similar and established prediction tools used in other areas, such as cardiovascular disease and breast cancer.
Basis for joint decisions
The lead author of the study is Jennie Larsudd-Kåverud, a doctoral student in Obstetrics and Gynecology at Gothenburg University and Obstetrician at Sahlgrenska University Hospital:
The statistical models used in this study allowed us to distinguish people at risk at the same level as other prediction models widely used in health care. “
Jennie Larsudd-Kåverud, Doctoral Student in Obstetrics and Gynecology, University of Gothenborgos
Until now, there has been no tool in clinical use that predicts the risk of OASI during childbirth in the way this newly formed calculator does. The goal is to reduce the number of injuries by applying the right measures at the right time.
“Models developed provide both health professionals and pregnant women with a tool for assessing the risk of serious birth damage. If the risk is low, concerns can be moderate. If the risk is higher, it provides the opportunity for more careful public planning and prevention.”
Source:
Magazine report:
Larsudd-Kåverud, J., et al. (2025). Predicting the injury to the obstetric sphincter in the first and second vaginal tradition and after a caesarean section: development and validation of an intra -business model. Newspaper of clinical epidemiology. doi.org/10.1016/j.jclinepi.2025.111782.
