The maternal leukocyte count at admission for labor is indicative of early maternal postpartum infectious morbidity and adverse neonatal outcome

Objectives: Investigate the association between maternal leukocyte count at admission for labor and postpartum infectious maternal morbidity (PPIM) following vaginal delivery. Study Design: Retrospective cohort study, 2005–2017. Afebrile women, term, singleton, vaginal delivery included. Maternal leukocyte/differential at admission for labor and 24 h postpartum were analyzed as continuous values and quintiles. Pre/postpartum difference (Δleukocyte) was calculated. The primary outcome was maternal PPIM, early and late. The secondary outcome was adverse neonatal outcomes (ANO). Results: 58,174 eligible deliveries out of168,979 (34.4 %); 1068 (1.8 %) women with PPIM. The rate rose linearly from 1.4 % for the lowest admission for labor leukocyte quantile to 2.7 % for the highest quantile, p for trend <0.001. The women with early PPIM had significantly higher admission levels of leukocytes (mean): 12.04 ± 3.43 vs. 11.18 ± 2.86 × 10^3/μl; neutrophils, 9.48 ± 3.46 vs. 8.40 ± 2.67 × 10^3/μl; and monocytes 0.76 ± 0.25 vs. 0.72 ± 0.23 × 10^3/μl); p < 0.001 for all. The mean leukocyte count for women with PPIM diagnosis, including only postpartum fever, was 12.06 ± 2.64; significantly higher than in the non-PPIM group, p = 0.014. A Δleukocyte value of >3.7 × 10^3/μl is significantly associated with PPIM, aOR 2.10 [1.82–2.41]. No significant association between leukocyte count or Δleukocyte and maternal readmission rate due to infectious complications. 386 neonates (0.7 %) had records of ANO and 64 neonates (0.1 %) had records of neonatal sepsis, positive linear association; p for trend < 0.001. The maternal Δleukocyte value of >3.7 × 10^3/μl was found to be significantly associated with the risk for ANO, aOR 1.5[1.19–1.90]. Conclusion: In healthy women, an elevated level of the leukocyte count at admission for labor and the Δleukocyte are significant risk predictors of PPIM and ANO.