Gestational Differences and Cross-Domain Associations of Routine Inflammatory and Haemostatic Markers in Pregnancies with Uncomplicated Term Outcomes: An Exploratory Cross-Sectional Study

Background/Objectives: Gestational differences in individual biomarkers have been established, but concurrent inflammatory–haemostatic correlations may partly reflect gestational timing. This study describes routine-marker differences and explored adjusted associations in pregnancies subsequently confirmed to have uncomplicated term outcomes. Methods: Sixty-six distinct women contributed one sample each: 18, 21 and 27 in the first, second and third trimesters. CRP, NLR, D-dimer and fibrinogen were the primary markers. Analyses included multiplicity-corrected comparisons, age-adjusted log-linear models and partial rank correlations adjusted for gestational week and maternal age. Cross-domain tests formed a 13-association exploratory family. A sensitivity analysis omitted five internally inconsistent differential blood counts. Results: Trimester differences remained for CRP, D-dimer and NLR after Holm correction (all adjusted p < 0.001), but not fibrinogen (p = 0.120). Adjusted fibrinogen correlations were 0.481 with white blood cell count, 0.461 with neutrophils and 0.320 with NLR (Benjamini–Hochberg-adjusted p < 0.001, <0.001 and 0.032). After omitting the five records, the corresponding coefficients were 0.447, 0.421 and 0.321 (adjusted p = 0.002, 0.004 and 0.042). Most cytokine values were below the effective lower calibration boundary and were not quantitatively reliable. Conclusions: This outcome-restricted cross-sectional sample showed an exploratory fibrinogen–leukocyte co-variation after limited adjustment. The overlapping indices represent one association pattern, not independent biological confirmations. Residual confounding, selection and measurement limitations preclude causal or clinical interpretation.