Background

Depression is a highly debilitating psychological disorder that is estimated to affect 350 million people worldwide. According to a mental health survey conducted in 17 countries, approximately one in 20 people were found to have had an episode of depression.1 Also, depression was the second leading cause of years lost to disability in 2010.2 Depression is more common among adult women, with the incidence in adult women in most countries being nearly twice that seen in men.3,4 Postnatal depression is a type of depression experienced by a mother following childbirth, typically arising from the combination of hormonal changes, psychological adjustment to motherhood and fatigue.5-7 It is a common mental health disorder which is estimated to affect 10-15% of all mothers in the postpartum period.5-7 Postnatal depression can be diagnosed by using the Diagnostic and Statistical Manual (DSM IV-TR) of mental disorders criteria,8 but for research purposes there are different tools such as the Edinburgh Postnatal Depression Scale, and Kessler 6 and 10 (K6 and K10) to detect postnatal depression.9

Postpartum depression is often unrecognized and must be distinguished from "baby blues".10 Symptoms of postnatal depression include low mood lasting much longer than baby blues.10 Some women with postpartum depression may have suicidal and infanticidal ideation, but they are reluctant to disclose this information unless asked directly.10 Postnatal depression is a severe form of depression that lasts more than two weeks, starts within a month of giving delivery8,10 and affects the individual's ability to function including caring for the baby.11 One systematic review found that in the first three months after childbirth, 14.5% of women have an episode of minor or major depression with nearly 40% of these women having experienced symptoms during pregnancy.11,12 Postnatal depression has a considerable burden on partners and close family members, affecting social and leisure activities and causing financial problems within the family.13-15 Also, postnatal depression has an adverse effect on the marital relationship13-15 and a detrimental impact on the partner's mental health.15

There has been significant research in developed countries on the risk factors for postnatal depression. Meta-analyses of these studies have identified past history of psychopathology, emotional disturbance during pregnancy, difficult marital relationships, inadequate social support and stressful life events as the primary risk factors for developing postnatal depression.7,16 Mothers with postnatal depression are more likely to have an unhealthy lifestyle, including poor diet and sleep patterns, compared to mothers free of postnatal depression.17-19 Women with postnatal depression tend to stop breastfeeding earlier than non-depressed mothers.20-22 Postnatal depression was associated with underweight, stunting and decreased mental development.23 It is well recognized that postpartum depression can have negative effects on early infant growth,24-28 with these effects potentially more pronounced in low-income countries with less favorable environments.26 Despite some evidence of higher risk for depression, most low-income and ethnic minority women remain undiagnosed or untreated for postnatal depression.29

Postnatal depression is a significant public health concern with wide-ranging negative consequences for women and their children. Literature reveals that children of mothers with postnatal depression are at an increased risk of behavioral, cognitive and social impairment.30,31 Postnatal depression is associated with impairment of the mother-infant bond which can result in longer term disruption of the emotional and cognitive development of the infant.7 Mothers with postnatal depression may be less able to interpret and respond appropriately to infant signals; they show more negative than positive emotions toward their infants and are more intrusive in their interactions with their infants.32

There are conflicting results from studies examining the effects of postnatal depression on infant growth. A study conducted in low-income countries revealed that higher postnatal depressive symptoms at five months were significantly associated with reduced infant weight gain between five and nine months, increased infant physical health concerns and nighttime awakening at nine months.33 In comparison, a study conducted in South Africa showed no clear effects of postnatal depression on child growth, although postnatal depression at two months was found to be associated with low infant weight at 18 months.34 A study conducted in Malawi found a significant association of postnatal depression with infant stunting,35 an indicator of long-term malnutrition, whereas a Nigerian study found that infants of mothers with postnatal depression had significantly poorer growth at three and six months when compared with controls.20 Infants of mothers with postnatal depression were more likely to have episodes of diarrhea and other infectious illnesses than infants of mothers free of postnatal depression.20 All of the studies conducted in South Africa, Malawi and Ethiopia identified a high prevalence of postnatal depression (34%, 26% and 33%, respectively), but failed to identify significant associations between postnatal depression and reduced infant weight.34-36 A study conducted in Zambia revealed that adverse infant health outcomes such as diarrhea, incomplete vaccination, reduced infants weight and length were proportionally greater in infants of mothers with postnatal depression.37 This study also reported an association between postnatal depression and the adjusted mean difference in infant weight and length in comparison to mothers free of postnatal depression.37 In Ethiopia, "maternal common mental disorder" was not associated with adverse infant development in any aspects.38^(p.2-12) Such conflicting results, coupled with the absence of any systematic reviews focused on the impact of maternal postnatal depression on infant growth in sub-Saharan African countries, indicate the need for clarification of the effects of maternal postnatal depression on infant development. A preliminary search for systematic reviews on this topic was performed in PubMed, CINAHL, DARE and PROSPERO. No existing systematic reviews that reported on the impact of maternal postnatal depression on infant growth in sub-Saharan African countries were identified in these databases.

Therefore, this systematic review will seek out the best available evidence regarding the impact of maternal postnatal depression on infant growth in sub-Saharan African countries. If a positive association is found, therapies could be targeted at women with postnatal depression to improve both maternal and infant outcomes.

Inclusion criteria

Types of participants

This review will include infants aged one year or younger. Infants who live in sub-Sahara African countries during their first year of life are included. Infants with congenital abnormalities will be excluded.

Types of exposure

This review will consider studies that examine the growth of infants whose mother has postnatal depression compared with the growth of infants of mothers who do not have postnatal depression. Postnatal depression is defined as depression that starts within one month after childbirth and whose symptoms last more than two weeks. We can measure postnatal depression by using the Diagnostic and Statistical Manual of Mental disorders or Edinburgh Post-natal Depression Scale and self-reporting questionnaire-20. This review will exclude studies that have been conducted on mothers with pre-existing psychological disorders.

Outcomes

This review will consider studies that include the following outcome measures: infant growth measured by any of the anthropometric measurements, such as weight for length, weight for age, length for age and head circumference. Infant's weight and length measured at three, six and nine months of postpartum period will be considered. Length of an infant will be measured using length board in a recumbent position. The weight of an infant can be measured by solidly built and durable electronic (digital reading) scale, UNISCALE39 (made by UNICEF), which measures up to 150 kg, to a precision of 0.1 kg (100 g) and allows tared weighing. The growth of the infant assessed based on the World Health Organization child growth standards39 will be considered.

As secondary outcomes, infant development measures (cognitive, language and motor developments) will be considered. For this purpose, studies that used Bayley's scales of infant development40 will be included.

Types of studies

This review will consider both experimental and epidemiological study designs including randomized controlled trials, non-randomized controlled trials, quasi-experimental studies, before and after studies, prospective and retrospective cohort studies, case control studies and analytical cross-sectional studies.

Search strategy

The search strategy aims to find both published and unpublished studies. A three-step search strategy will be used in this review. First, an initial limited search of MEDLINE/PubMed and CINAHL will be undertaken followed by an analysis of the text words contained in the title and abstract, and the index terms used to describe the article. A second search using all identified keywords and index terms will be undertaken across all included databases. Third, the reference list of all identified reports and articles will be searched for additional studies. Studies published in English language will be considered for inclusion in this review. Studies published between 2001 and 2014 will be considered for inclusion in this review, because in sub-Saharan Africa, there was no publication on effects of postnatal depression on infant growth before 2001.

The databases to be searched will include:

MEDLINE, EMBASE, Google Scholar, PsycInfo, Web of Science and CINAHL.

The search for unpublished studies will include:

MedNar and ProQuest.

Initial keywords will be: Postnatal, postpartum, depression, mental disorders, infant growth, weight, length, underweight and stunting.

Assessment of methodological quality

Articles selected for retrieval will be assessed by two independent reviewers for methodological validity before inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix I). Any disagreements that arise between the reviewers will be resolved through discussion or consultation with a third reviewer.

Data extraction

Data will be extracted from articles included in the review using the standardized data extraction tool from JBI-MAStARI (Appendix II). The data extracted will include specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. The authors of primary studies will be contacted by email in case there is incomplete information.

Data synthesis

Quantitative data will, wherever possible, obtained and pooled in statistical meta-analysis using Revman 5 software. All results will be subjected to double data entry. Before conducting the meta-analyses, heterogeneity will be statistically assessed using the standard [chi]² and visual inspection of the meta-analysis output on a forest plot. Owing to the possibility of low power, if there are few studies, we will use a significance level of P < 0.1 to protect against the possibility of falsely stating that there is no heterogeneity present. Data will also be explored using subgroup analyses based on the different study designs included in this review. Effect sizes expressed as weighted mean differences (for continuous data) and their 95% confidence intervals will be calculated for analysis. Effect sizes expressed as standardized mean differences (for continuous data) and their 95% confidence intervals will be calculated using the DerSimonian and Laird method. For categorical variables, odds ratio or risk ratio and their 95% confidence interval will be calculated. Where statistical pooling is not possible, the findings will be presented in narrative form.

Acknowledgments

The authors are grateful to Joanna Briggs Institute and Jimma University JBI Collaborating Center and Jimma University for their technical support.

Appendix I: Appraisal instruments

MAStARI appraisal instruments

Appendix II: Data extraction instruments

MAStARI data extraction instrument

References