Haemoglobin levels after childbirth may flag postpartum depression

New research in women with vaginal births has found a significant association between haemoglobin levels immediately after childbirth and the likelihood of developing symptoms of postpartum depression (PPD).

The analysis included 2,672 women who participated in the TRanexamic Acid for Preventing Post-partum Haemorrhage After Vaginal Delivery trial conducted in France. Of these, 1,115 (43.6 percent) had anaemia (haemoglobin <11 g/dL) in the immediate postpartum and 369 (13.8 percent) had PPD symptoms at 2 months. [BJOG 2025;doi:10.1111/1471-0528.18289]

Haemoglobin showed a linear association with PPD symptoms, such that each 1-g/dL–level increase in haemoglobin level reduced the risk of PPD symptoms by 9 percent (adjusted relative risk [aRR], 0.91, 95 percent confidence interval [CI], 0.82–0.997).

Postpartum haemoglobin was specifically associated with moderate depressive symptoms (aRR, 0.84; 95 percent CI, 0.72–0.98) but not with severe depressive symptoms (aRR, 0.95; 95 percent CI, 0.84–1.07).

“These results are consistent with studies conducted on nonpregnant populations reporting an association between anaemia and depression symptoms,” according to the investigators. [BMJ Open 2012;2:e000551; Acta Psychiatr Scand 2016;134:150-160]

How anaemia factors in depression may be related to increased cerebral blood flow, as a compensatory neuroprotection mechanism to protect the brain from hypoxia, they explained. “The cerebral blood flow is particularly increased in frontal, middle temporal, and hippocampal regions which are involved in depression pathways.” [J Gerontol A Biol Sci Med Sci 2012;67:963-969]

Anaemia can also lead to shortness of breath and fatigue, which in turn may reduce social activity and contribute to the onset of depressive symptoms, the investigators said. [Ann Oncol 2004;15:979-986]

“Furthermore, iron is involved in the metabolism of dopamine, serotonin, and GABA which are implicated in depression pathogenesis. Iron status could then influence emotional behaviours and mental health by altering neurotransmitter homeostasis,” they added. [J Nutr Biochem 2014;25:1101-1107]

Additional findings

When differentiating two levels of PPD severity, haemoglobin was specifically associated with moderate symptoms, with a 16-percent risk reduction for each 1-g/dL increase in haemoglobin levels (aRR, 0.84, 95 percent CI, 0.72–0.97), but not with severe symptoms. The investigators postulated that among women with severe PPD symptoms, the effect of haemoglobin on PPD might have been masked by the more powerful influence of risk factors such as adverse life experiences.

Looking at maternal place of birth, an association between haemoglobin and PPD was observed among European-born women but not among non-European-born women, who had a much higher prevalence of PPD symptoms.

“In our study, most non-European-born women were from Africa. In these women, other risk factors such as social vulnerability might have outweighed the role of haemoglobin,” the investigators said. “Another possible explanation is that in non-European-born women, anaemia is more frequently chronic,” with chronic anaemia being possibly better tolerated than acute anaemia and having less impact on emotional wellbeing, they added. [https://www.who.int/data/gho/data/themes/topics/anaemia_in_women_and_children]

Taken together, the present data underscore the importance of precise characterization of PPD risk factors. “They suggest that some risk factors are specific to some population subgroups or some profiles of PPD symptoms,” according to the investigators.

In the study, PPD symptoms at 2 months post-partum was defined as an Edinburgh Postnatal Depression Scale score of ≥11.