Predicting PTB within 1w in tPTL

<b>Objectives:</b> To investigate the association between inflammatory indices derived from complete blood count (CBC) and delivery within one week for threatened preterm labor (tPTL) in order to contribute to the management algorithm for women with tPTL.<b>Materials and methods: </b>We conducted a retrospective cohort study of women with a singleton pregnancy and tPTL admitted to a large tertiary referral hospital between October 1, 2022, and May 31, 2023. After exclusion, the study groups were formed with 42 women who gave birth within one week of admission (group 1) and 84 women who gave birth later than one week after admission (group 2). The comparison focused mainly on whether there was a difference between the two groups in the systemic immune inflammation index (SII), systemic inflammatory response index (SIRI) and pan-immune inflammation value (PIV), as well as other inflammatory indices.<b>Results:</b> Monocyte count, monocyte-to-lymphocyte ratio (MLR), SIRI and PIV were significantly higher in group 1 (p=0.038, 0.019, 0.029 and 0.037, respectively) and receiver operating characteristics curve analysis for discriminatory power to predict PTB within one week revealed area under the curve values of 0.613, 0.628, 0.620 and 0.614, respectively. The overall predictive power showed no significant superiority between the individual parameters.<b>Conclusions:</b> Our preliminary results showed an association between increased inflammatory indices and an increased risk of delivery within one week in women with tPTL. In particular, SIRI and PIV may facilitate decision-making in the management algorithm for women with tPTL. Further randomized controlled trials with a larger cohort are needed to better define efficacy and limitations.