Having a baby is one of life’s most fulfilling experiences. But this huge life change is also extremely stressful. Research has shown that in high-income countries, 10 to 15 per cent of mothers suffer from postnatal depression. And as well as the distress of the mother, postnatal depression can also affect the cognitive and emotional development of the infant.

In developing countries, by contrast, where attention tends to focus on seemingly more pressing health problems such as infectious diseases, postnatal depression has received little attention. Yet recent studies have shown that as many as 25–30 per cent of new mothers in these countries suffer from postnatal depression – a prevalence almost double that in the developed world.

The reasons for this are likely to be complex and varied. Possibilities include the lower status of women relative to men in many countries and their lack of autonomy, the birth of a girl in regions where there is a strong preference for male children, poor housing, isolation and poverty.

And it is not just the mother at risk: postnatal depression in low-income countries also impacts on the infant’s cognitive and emotional development, and also appears to play a crucial – and previously unrecognised – role in the baby’s physical growth and survival.

Malnutrition and infection

“The environment is frequently more hostile in a developing country,” points out Dr Atif Rahman at the University of Manchester. “There’s more infection and less sanitation. The mother has to boil water before using it, and be vigilant about washing her hands and making sure every utensil is clean. That’s a lot of pressure on somebody who’s struggling to get through the day anyway.”

So as well as harming the mother, postnatal depression may well affect her mothering. “If a mother is depressed and unable to do all those things, her infant might not get all the nutrients it needs. The child might also be exposed to infection such as diarrhoea, which strips vital nutrients from its body. The mother’s depression might prevent her from responding appropriately to her child’s illness, or from taking her infant to be vaccinated against infection in the first place. All these things are going to impact on the child’s health and growth.”

In Ethiopia, where up to 10 per cent of infants die in their first year of life, maternal depression could be a deciding factor in whether the child survives at all. “People tend to see infectious diseases as the main problem in Ethiopia,” says Dr Charlotte Hanlon at the London School of Hygiene and Tropical Medicine. “But 50 to 60 per cent of Ethiopian children who die from infectious diseases do so because they are malnourished and don’t have the strength to fight the illness.”

Dr Hanlon is currently planning an epidemiological study to establish whether postnatal depression is a problem in Butajira, Ethiopia – and whether it impacts on infants’ growth. “If we find that postnatal depression does affect children’s nutrition in Ethiopia, then far from being a separate issue about quality of life, maternal mental health becomes crucial to the infant’s very survival.”

One of the particular challenges of the project is to find a measure of depression that is appropriate to that particular culture. “We’ll ask local clinicians what they would consider to be psychiatric illness, as opposed to distress, and make this our benchmark, rather than using one based on Western standards,” explains Dr Hanlon.

“Once we’ve identified our cohort of depressed mothers, we’ll interview them again to find out how they perceive themselves: whether they think there’s anything wrong, what they attribute their difficulties to, and what kind of help, if any, they seek.” Although this will be the first study looking at postnatal depression in Ethiopia, previous studies looking at depression generally indicate that most people with depression were aware that something was not right, or was holding them back. “A certain proportion said they were ‘depressed’, but others talked about bewitchment or the evil eye of jealous neighbours, who put a curse on them, to explain their incapacity.”

Dr Hanlon believes that understanding how people recognise and explain depression in that culture is vital groundwork that will make it possible to develop appropriate interventions further down the line. “We’re not going to be giving people Prozac,” she asserts. “We’ll be looking for something that is more meaningful and relevant to their culture.”

Lady health workers

This is precisely what Dr Rahman is now doing in Pakistan, where he has already shown that postnatal depression and its impact on infant growth is a significant problem. “In the West, treatments like psychotherapy and antidepressants have been successful for postnatal depression,” he says. “But we can’t simply transfer these to developing countries, which have very different healthcare systems and cultural beliefs. We need to tailor the intervention to the setting.”

The postnatal setting in Pakistan is dominated by armies of female primary healthcare workers, known as ‘lady health workers’, who visit mothers on a monthly basis for up to a year after the birth of the child, advising on mother and child health and parenting. Since 1994, the Pakistan government health system has recruited and trained approximately 47 000 lady health workers.

Into this well-established and successful practice, Dr Rahman aims to integrate a psychological intervention aimed at depressed mothers. The intervention, which will be developed and tested in a randomized controlled trial over the next three years, is a form of cognitive behavioural therapy that is delivered by the lady health worker during her monthly visits.

“The lady health worker will give the depressed mother the same kind of advice about nutrition, sanitation and so on that she gives non-depressed mothers. It’s just presented in a different way, within a psychological framework,” he explains.

“The lady health worker will support the depressed mother through empathic listening and positive reinforcement. She will give the mother a set of tasks, broken down into small, doable steps. On her next visit, the health worker will show the mother that by doing these tasks she’s achieving measurable results: the infant is growing or thriving more. This gives the mother a sense of empowerment and makes her feel more confident about her parenting capabilities. We’re hoping that this in turn will improve the mother’s mood – and that the whole thing will impact positively on the infant’s development – emotional as well as physical.”

He stresses the importance of presenting the intervention in a way that will be acceptable within that particular culture. “In some regions, depression simply isn’t accepted as a problem, or is stigmatised. If you try and tell people the mother is depressed, she herself, and her husband and wider family, will all resist the diagnosis and say ‘there’s no mental health problem, why are you wasting our time?’”

So, says Dr Rahman, more supportive messages will be used. “We’ll say we’re working for optimal health of the child, and encourage families to support the mother for the sake of the child. The key message will be that ‘a healthy mother leads to a healthy child’. This agenda is more likely to be accepted, because the child is important for everyone – in-laws, grandparents and father. And hopefully there will be tangible, measurable results – they will see that the child is growing better and has less diarrhoea – to reinforce the message.”

While it might seem anomalous to look at postnatal depression in developing countries, where other health problems seem so compelling, it is likely that these are precisely the places where mental health problems are likely to be at the worst – and contributing significantly to the severity of other health problems.

“I think it’s a mistake to neglect mental health, even in a very extreme setting such as Ethiopia,” asserts Dr Hanlon. “It ignores the role mental health plays in maintaining physical health and in the development of the community.”

Dr Atif Rahman holds a Wellcome Trust Career Development Fellowship in Clinical Tropical Medicine and Dr Charlotte Hanlon holds a Wellcome Trust Training Fellowship in Tropical Clinical Epidemiology.