Differential circulating CD8+ memory T-cell activation profiles in nulliparous and multiparous women undergoing induction of labor

Abstract Multiparous women typically give birth faster than nulliparous women, but the exact mechanisms underlying this differential speed remain unclear. As multiparous women have elevated inflammatory mediators in gestational tissues and circulation compared to nulliparous women, immunological memory acquired from prior childbirth may contribute to these differences. We conducted a prospective longitudinal study involving 34 nulliparous and 30 multiparous women undergoing induction of labor (IOL). Maternal peripheral blood samples were collected at three time points: before IOL, during the latent phase, and during the active phase of labor. Circulating CD8⁺ memory T-cell subsets—including central memory (T CM ), stem cell memory (T SCM ), effector memory (T EM ), terminally differentiated effector memory (T EMRA ), and CXCR5⁺ memory T-cells (T CXCR5⁺ )—as well as their activated populations (indicated by CD69⁺ expression), were analyzed using multicolor flow cytometry. Comparisons between parity groups and across sampling time points were analyzed using linear mixed-effects models. Longitudinal analysis showed that multiparous women exhibited elevated percentages of activated TEM cells and activated TEM cells after IOL, which were higher than those observed in nulliparous women, whereas nulliparous women showed reduced total TCM percentages after IOL ( P < 0.05). These findings suggest parity-associated differences in circulating CD8⁺ memory T-cell activation profiles during IOL.