To our knowledge, this is the first study showing an association between postnatal depression and infant diarrhoeal morbidity in a low‐income developing country. We did not rely solely on mothers' reporting as this may have biased our findings—data were verified from other close members of the family. The exposure status—that is, maternal depression—was determined in the antenatal period and reassessed 3 months postnatally by experienced clinicians using a standardised interview.
However, the findings should be generalised with caution as the study was carried out in only one subdistrict of Rawalpindi. Although potential confounders were carefully adjusted for in the analysis, it is possible that an unmeasured sociocultural or environmental factor peculiar to the study area might account for the association observed.
Our study did not examine the process by which maternal depression led to higher rates of diarrhoeal infection in infants. Such associations are presumably the result of complex causal chains, and there may be different ways in which risk factors work together to influence the outcome. Factors such as parental education, social support, socioeconomic status and infant nutritional status might be important moderators in the association. Similarly, factors such as quality of infant care and feeding practice could mediate the effects of depression on diarrhoeal morbidity. Further studies in different settings and with larger sample sizes would be required to clarify the nature of these interactions.
What is already known on this topic
- Low‐income countries have high rates of diarrhoeal illness in infants.
- Rates of postnatal depression in these countries are also high.
What this study adds
- Infants of postnatally depressed mothers have more episodes of diarrhoea per year than infants of psychologically well mothers.
- This association is independent of the effects of known factors such as undernutrition, socioeconomic status and parental education.
Nevertheless, depression is clearly a disabling disorder. Patel et al3
found that in India postnatally depressed mothers scored significantly higher on the Brief Disability Questionnaire (an 8‐item questionnaire that rates current problems in carrying out daily activities), spending about twice the number of days in the previous 30 days unable to complete their daily activities. It is plausible that disability associated with depression may interfere with child‐care activities, hence putting the child's health at increased risk. This is supported by substantial evidence that shows the negative effect of postnatal depression on the mother–infant interaction and psychological development.9
Several studies from Western countries have also shown an association of maternal depression and child neglect with physical abuse.10,11,12
However, links between preventable infectious illnesses such as diarrhoea and maternal psychological state around childbirth in low‐income settings have not been extensively researched.
The Global Burden of Disease Study, using mortality and years lived with disability, ranks diarrhoea and unipolar depression as the second and fourth most burdensome disorders, respectively.13
The association between these two major public health problems indicates a need for integrated and holistic interventions that could be applied in a pragmatic way to reduce the immense burden on mothers and children in the developing countries.