This study shows that maternal depressive disorder in the third trimester of pregnancy is associated with an increased risk of LBW in a low-income developing country, and that this association is independent of the effects of poverty and maternal nutritional status represented by the mother's BMI. In addition, longitudinal follow-up of these infants over a 1-year period showed that maternal depression is associated with growth retardation independent of the effects of LBW (12
). Thus, foetal disadvantages associated with maternal depression in pregnancy are two-fold: LBW and subsequent growth retardation. These are accompanied by continued maternal depression during postnatal period (11
). These findings must be relevant to the very high but largely unexplained rate of child undernutrition in the region despite adequate food supply.
The study has a number of strengths including a community-based population from a defined geographical rural area of Pakistan, the measurement of maternal depression by experienced clinicians using a standardized instrument and selection of a very similar non-depressed group. The main limitation of the study is that we could not measure haemoglobin or gain any other objective indicator of physical ill health in the mother. It is possible that iron-deficiency anaemia, for example, could be a confounder in the association between depression and LBW. On the other hand anaemia does not appear to be associated with depression (20
), and we excluded mothers who said that they had a diagnosed condition or/and regularly took any medication or who had current problems with their pregnancy necessitating medical advice. We also found no significant association between depression or LBW and BMI or maternal height.
Poverty is another potentially important possible confounder. Assessments show only two out of 290 subjects were short of money for food in the previous month indicating hardly any suffered from absolute poverty (22
). Our measures of more subtle levels of poverty might be biased as depressed women might selectively recall debt due to their mental state, and may ‘look’ poorer due to their depression. Nevertheless, these were felt to be the best measures because household income can be an unreliable measure in this settings (23
). While associations were found between poverty thus measured and LBW, multivariate analyses shows that these do not confound the association seen between maternal depression and LBW in this population. In more impoverished communities, however, poverty may assume a greater role in determining LBW.
Depressed and non-depressed mothers did not differ significantly in their height, precluding it as a confounding factor in this study. Maternal depression was a stronger predictor of LBW than poor maternal nutritional status (defined by a BMI of < 18.5). Poor nutritional status is the principal cause of LBW in developing countries (24
) but in the largely food sufficient region of south Asia, maternal depression could play a greater role. Indeed, the reasons for the disproportionately large rates of undernutrition in this region are not fully understood, the problem being referred to as the ‘Asian enigma’ (25
). Cigarette smoking and malaria during pregnancy, are other leading causes of LBW (24
) but these were not prevalent in our study area. The mean difference of 112 g between babies of depressed and non-depressed mothers gains more significance when the ubiquitous nature and high prevalence of depressive disorder is taken into account. In this study 25% of women were depressed, but in other studies, higher rates have been reported in women with less education and more young children to look after (26
). Depression, through its associations with poverty, poor physical health and unhealthy lifestyle (e.g. smoking, poor eating habits, inappropriate health-seeking) could also act as a moderator for these risk factors.
Low birthweight has important long-term health consequences. LWB babies are more likely to have continued growth retardation in early life and poorer intellectual development (28
) and are at an increased risk of depression in adolescence (30
). Diagnosis and treatment of depression during pregnancy could not only reduce the burden on mothers but could be an important preventive action for both physical and mental health of the off-spring. We are currently involved in a trial of treating depression to see if this improves neonatal outcomes in rural Pakistan.
In developed countries, detection and management of perinatal depression has made significant progress (31
). Studies have also shown that greater social support and better psychosocial health facilities for antenatally depressed mothers in low-income communities can lead to improved neonatal outcomes (32
). Such psychosocial interventions suitable for developing countries should be developed to tackle these associated problems of immense public health significance. There is the opportunity to take up such an initiative now as part of the goal of reducing LBW incidence by at least one-third between 2000 and 2010, one of the major goals in ‘A World Fit for Children’, the Declaration and Plan of Action adopted by the United Nations General Assembly Special Session on Children in 2002 (1
). The reduction of LBW also forms an important contribution to the internationally agreed Millennium Development Goal (MDG) for reducing child mortality and is a key indicator of progress. These goals cannot be achieved by neglecting the mental health of mothers during pregnancy and after childbirth.