Systemic inflammation indices measured shortly before delivery are not associated with preterm birth in pregnant women with endometriosis

Endometriosis is a chronic inflammatory condition, typically associated with pelvic pain and menorrhagia, affecting 10% of women of reproductive age. Inflammation is known to contribute to pregnancy complications, including preterm birth. Recent evidence suggested that women with endometriosis have a higher risk of preterm birth. However, the underlying mechanism remains unclear. Systemic inflammation indices, increasingly used as markers of inflammation in pregnancy-related conditions, may provide insights into this association. In this study, we aimed to investigate whether systemic inflammation contributes to preterm birth in pregnant women with endometriosis. A total of 75 pregnant women with endometriosis confirmed at cesarean sections were included. Clinical and obstetric data were collected and compared with hospital-wide cesarean section data during the same period. Systemic inflammation indices were calculated from peripheral blood tests taken before delivery. Among the 75 women with endometriosis, 15 (20%) experienced preterm birth, which was significantly higher than the 11.4% incidence observed among all other women who delivered by cesarean section at our hospital during the same study period (p = 0.019). The increased incidence of preterm birth was observed across all subtypes of endometriosis. However, systemic inflammation indices, including systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), neutrophil to lymphocyte ratio (NLR), and pan-immune inflammation value (PIV), derived from blood tests shortly before delivery, did not differ significantly between women with endometriosis who had preterm birth and those who delivered at term. In conclusion, systemic inflammatory indices measured shortly before delivery were not associated with preterm birth in this cohort. Without evaluation of the localized uterine inflammation and systemic inflammation changes earlier in gestation, and the small sample size, our findings are hypothesis-generating and require confirmation in larger studies in the future.