Definition dependence of questionnaire-reported maternal temperature elevation in a retrospective registry cohort of women receiving neuraxial labor analgesia.

BACKGROUND

Questionnaire-reported maternal temperature elevation during neuraxial labor analgesia may vary depending on the outcome definition. We compared nested definitions and examined exploratory associations while addressing incomplete outcome linkage.

METHODS

This retrospective registry-based cohort comprised 3,409 labor-analgesia records from July 2022 through March 2023, with 1,658 (48.6%) having a linked questionnaire temperature outcome. The outcomes reported were a fever at or above 38.0 °C and any elevation in temperature. We used Firth penalized logistic regression for the sparse strict-fever endpoint, conventional logistic regression for the broader endpoint, multiple imputation with 50 imputed datasets for missing covariates, and inverse probability of outcome observation weighting (IPOW) for linkage sensitivity.

RESULTS

Strict fever was reported in 88/1,658 linked records [5.3%; 95% confidence interval (CI), 4.3%-6.5%], and any elevation was noted in 287/1,658 (17.3%; 95% CI, 15.6%-19.2%). IPOW-standardized estimates were 5.4% and 17.5%, respectively. Among 1,139 complete records, nulliparity had a large but imprecise association with strict fever [Firth-adjusted odds ratio (OR), 8.05; 95% CI, 2.51-40.76], whereas the dural puncture epidural estimate crossed the null (OR, 0.60; 95% CI, 0.35-1.02). For any elevation, age (OR per year, 1.08; 95% CI, 1.03-1.13), nulliparity (OR, 3.23; 95% CI, 1.86-5.63), and analgesia duration (OR per 2 h, 1.13; 95% CI, 1.06-1.20) were associated with higher odds; duration non-linearity remained exploratory (p = 0.002).

CONCLUSION

Observed questionnaire-reported temperature frequency was definition-dependent. Incomplete outcome linkage, sparse strict-fever events, uncertain temperature timing, and differential laboratory testing limit inference; the findings are exploratory and require prospective validation with continuous timestamped temperature measurement.