An association between plasma ferritin concentrations measured 48 h after delivery and postpartum depression

Context: Iron deficiency is the most common nutritional problem experienced by childbearing women, and postpartum depression (PPD) is the most common psychiatric disorder seen during the first year after delivery. The possible link between iron deficiency and PPD is not clear.

Objective: To evaluate whether iron status 48 h after delivery was associated with PPD. Our hypothesis was that iron deficiency would be associated with PPD.

Design: This was a prospective cohort study of depression-free women studied in the postpartum period.

Setting: Women who give birth at obstetric units in several general hospitals in Spain.

Participants: A subsample of 729 women was included in the present study after exclusion of women with high C-reactive protein (CRP) and other diseases known to interfere with iron metabolism.

Main outcome measures: We evaluated depressive symptoms at 48 h, 8 weeks and 32 weeks postpartum and used a diagnostic interview to confirm the diagnosis of major depression. A blood sample obtained 48 h after delivery was used to measure the following iron storage parameters: ferritin, transferrin (Tf), free iron and transferrin saturation (TfS) and the inflammatory marker CCRP.

Results: Overall, the women in the study had low iron concentrations (8.8 ± 6.9 μmol/L) and low TfS (12.6 ± 9.6%) but normal ferritin and Tf concentrations. A total of 65 women (9%) developed PPD during the 32 week postpartum period; these women also had a lower ferritin concentration (15.4 ± 12.7 μg/L vs. 21.6 ± 13.5 μg/L, P = 0.002). A strong association between ferritin and PPD was observed (odds ratio = 3.73, 95% CI: 1.84-7.56; P = 0.0001 for ferritin cutoff value of 7.26 μg/L). In our study, ferritin concentrations have a high specificity but low sensitivity in predicting PPD.

Conclusions: These findings support the role of iron in the etiology of PPD and the use of ferritin as a marker of iron deficiency in the postpartum period. We believe that this topic deserves further investigation.