Summary

Background: Fetal weight estimation at term is a challenging clinical task.

Objectives: To evaluate the association between peripheral white blood cell (WBC) count of the laboring women and neonatal birth weight (BW) for term uncomplicated pregnancies.

Methods: We conducted a single-center, retrospective cohort study (2006–2021) of women admitted in the first stage of labor or planned cesarean delivery. Complete blood counts were collected at admission. BW groups were categorized by weight (grams): < 2500 (group A), 2500–3499 (group B), 3500–4000 (group C), and > 4000 (group D). Two study periods were used to evaluate the association between WBC count and neonatal BW.

Results: There were a total of 98,632 deliveries. The dataset analyses showed a lower WBC count that was significantly and linearly associated with a higher BW; P for trend < 0.001 for women in labor. The most significant association was noted for the > 4000-gram newborns; adjusted odds ratio 0.97, 95% confidence interval 0.96–0.98; P < 0.001; adjusted for hemoglobin level, gestational age, and fetal sex. The 2018–2021 dataset analyses revealed WBC as an independent predictor of macrosomia with a significant incremental predictive value (P < 0.0001). The negative predictive value of the WBC count for macrosomia was significantly high, 93.85% for a threshold of WBC < 10.25 × 10³/µl.

Conclusions: WBC count should be considered to support the in-labor fetal weight estimation, especially valuable for the macrosomic fetus.