Overview: Why the stage of labor matters for cesarean scars
Women who undergo cesarean births during advanced labor face a significantly higher risk of developing scars inside the uterus near the cervix. This unexpected finding from University College London researchers helps explain why some women are more likely to have preterm births in later pregnancies. The study, published in the American Journal of Obstetrics & Gynecology, adds a crucial piece to the growing understanding of how surgical timing affects long-term reproductive health.
What the study looked at
The research focused on the location and healing of cesarean scars in women who gave birth while labor was actively progressing. The team used transvaginal ultrasound to assess the scar position four to twelve months after birth in a group of 93 women who had cesareans during active labor. Active labor was defined as the cervix dilated to at least four centimetres and, in many cases, approaching eight centimetres. The goal was to determine whether the scar’s position within the womb could be predicted by how far labor had progressed and how that positioning might influence healing and future pregnancy risk.
Key findings: scar position and healing
The study found a clear relationship between cervical dilation during labor and scar location. Specifically, for each additional centimetre of cervical dilation, the scar moved about 0.88 millimetres closer to the cervix and lower in the uterus. About 58% of the scars sat in the upper part of the womb, while 21% were near the cervix and another 21% resided within the cervix itself. Those cesareans performed later in labor were eight times more likely to produce scars near or within the cervix compared with earlier cesareans.
Healing quality also varied by scar position. Scars closer to or within the cervix were more prone to “niches”—small gaps in the uterine wall that can collect blood and potentially lead to infertility, irregular bleeding, or complications in subsequent pregnancies. In contrast, higher-placed scars tended to heal more effectively.
Why this matters for future pregnancies
Previous work by the same researchers linked internal scar proximity to the cervix with higher odds of preterm birth in later pregnancies. The new findings suggest that late-labor cesareans not only increase the chance of a problematic scar location but may also predispose women to future pregnancy challenges due to impaired scar healing.
Lead author Dr. Maria Ivan notes that the stage of labor during cesarean births has meaningful implications for long-term reproductive health. She emphasizes that awareness of scar location could inform follow-up care plans and strategies to mitigate preterm birth risks in subsequent pregnancies.
Clinical implications and future directions
The researchers advocate for more research into cesarean-scar healing and its wider gynecologic impact. By understanding how labor stage affects scar formation, clinicians could tailor postnatal monitoring and counseling for women who had advanced-labor cesareans. There is also potential to refine surgical techniques to minimize scar formation near the cervix and improve healing outcomes.
Context: rising cesarean rates
The study comes amid rising cesarean rates in high-income countries. In England, cesarean deliveries accounted for 42% of all births in 2023/24, underscoring the importance of understanding long-term consequences and optimizing care for women who undergo these procedures.
Conclusion
Advanced-labor cesareans are linked with an increased risk of cervical-near uterine scarring and impaired healing, which in turn may heighten the risk of preterm birth in future pregnancies. The findings highlight the need for enhanced postnatal follow-up, potential adjustments in surgical technique, and continued research to improve outcomes for women and their babies.
Quotes from researchers
Lead author Dr. Maria Ivan: “Our study shows the stage of labor at cesarean has real implications for where the scar forms and how it heals.”
Co-author Professor Anna David: “These insights can help shape future care for women with advanced-labor cesareans and reduce the risk of complications down the line.”
