Maternal Serum Ferritin Concentrations in Pregnancies Complicated by Preterm Labour or Preterm Prelabour Rupture of Membranes: A Comparative Observational Study

Abstract

Background: Ferritin reflects both iron stores and acute-phase inflammation. Its concentration may differ in pregnancies complicated by spontaneous preterm labour or preterm prelabour rupture of membranes (PPROM), but contemporaneous measurement after clinical presentation cannot establish prediction.

Objective: To compare maternal serum ferritin concentrations among women with PPROM, spontaneous preterm labour, and uncomplicated pregnancies at 28–36+6 weeks of gestation, and to describe associated maternal laboratory findings and perinatal outcomes.

Methods: This hospital-based comparative observational study enrolled 210 pregnant women at a tertiary centre in Central India from June 2024 to January 2026: 70 with PPROM, 70 with spontaneous preterm labour, and 70 controls. Serum ferritin was measured by immunoturbidimetry. Continuous outcomes were compared using Welch's one-way analysis of variance with Games–Howell pairwise tests; categorical variables were compared using Pearson's chi-square test.

Results: Mean (SD) ferritin was 20.89 (10.10) ng/mL in controls, 59.39 (40.30) ng/mL in PPROM, and 41.23 (25.20) ng/mL in preterm labour (Welch F(2, 109.01)=45.40; p<0.001). Compared with controls, the mean difference was 38.50 ng/mL for PPROM (95% CI, 26.63–50.37) and 20.34 ng/mL for preterm labour (95% CI, 12.61–28.07); PPROM also exceeded preterm labour by 18.16 ng/mL (95% CI, 4.67–31.65). Leukocyte counts were higher and haemoglobin was lower in both complication groups, whereas C-reactive protein positivity did not differ. Gestational age at sampling and documented vaginitis/urinary tract infection also differed substantially among groups. Infants in the PPROM and preterm-labour groups delivered earlier, weighed less, and were more often admitted to neonatal intensive care.

Conclusions: Maternal ferritin was higher at presentation with PPROM or spontaneous preterm labour than in controls. Because ferritin was measured after diagnosis and the groups differed in gestational age and infection status, these data support ferritin as a concurrent inflammatory correlate, not as a validated independent screening or predictive test. Prospective studies with prespecified sampling, multivariable adjustment, and external validation are required.