Fig. 2

Association between maternal serum hepcidin concentration and spontaneous preterm birth in the PALUFER study. Fit and P-values derived from a logistic regression of preterm birth incidence (proportion) against log(hepcidin nmol/ml). Stippled lines are 95% confidence interval. Rugs at top and bottom indicate where preterm birth (red) and non-preterm birth (green) deliveries lie. ANC1 and ANC2 are the scheduled study antenatal visits. The regression slopes are 0.01 (95% CI − 0.20:0.22) for ANC1 and 0.38 (0.10:0.66) for ANC2 per unit log(hepcidin)