Global prevalence estimates of depression in the perinatal period range from 4% to over 50%, with the highest burden in low-resource settings, making depression a public health priority.1 In addition to the effect of maternal depression on social functioning, physical health, and risk of suicide, observational evidence suggests that maternal depression is associated with a higher risk of multiple negative child outcomes, including physiological stunting, socioemotional difficulties, problems with school readiness and performance, and depressive symptoms over the child's lifetime.1, 2 Women experiencing perinatal depression are at much higher risk of subsequent or recurrent episodes of depression than are those who do not have perinatal depression, and this chronic or episodic depression is most deleterious for numerous maternal and child outcomes.3, 4 This risk of intergenerational transmission of psychopathology is most heavily borne by poorer families and those in low-resource settings with little access to quality health care, thus exacerbating economic and social inequality.3
Research in context
Evidence before this study
Systematic reviews of psychotherapy interventions for depression have highlighted the scarcity of evidence for the long-term effects of psychotherapy on either maternal mental health or child outcomes. We searched for studies designed to evaluate interventions for perinatal depression in which the intervention lasted beyond 12 months postnatal (eg, booster sessions) or follow-up was more than 12 months after the completion of the intervention, that were published between Jan 1, 2002, and April 30, 2020. We limited our search to randomised clinical trials or meta-analyses. We did not place restrictions on language or country. We used Pubmed and Web of Science using the search terms “(maternal depression)” OR “(perinatal depression)” OR “(postpartum depression)” OR “(postpartum depression)” AND “(treatment)” OR “(therapy)” OR “(intervention)” OR “(psychotherapy)” OR “(cognitive behavioral therapy)” AND “(longer-term)” OR “(longer)” OR “(booster)”. We identified six randomised controlled trials specific to perinatal depression with the longer follow up period, ranging from 1·5 to 7·0 years. No studies used an extended duration design that continued past 12 months postnatal; two studies included a comparison group without depression. The most common intervention models were cognitive behavioural therapy and interpersonal therapy. Evidence generally showed that interventions improved outcomes, which then weakened over time so that, overall, there was little evidence of the effects of perinatal depression interventions that persisted beyond the perinatal period. Of the six studies, two reported some lasting effect. One study of 884 mother–child dyads assessed maternal and child outcomes 7 years after the end of a cognitive behavioural therapy intervention and found a lower rate of depression among mothers who received the intervention, but no significant effects on child outcomes. With this one exception, sample sizes were small, with studies having fewer than 60 participants per group available at follow-up.
Added value of this study
To our knowledge, this study, in rural Pakistan, was the first large, multi-year, randomised controlled trial focusing on both maternal and child outcomes in which individuals with depression received psychotherapy beginning prenatally. The extended duration psychosocial intervention evaluated in our study did not show evidence of meaningfully reduced depression symptom severity or improved child outcomes at the 3-year postnatal mark.
Implications of all the available evidence
Our findings highlight the challenges of implementing a peer-delivered, psychosocial intervention over a longer period in low-resource community settings. Lessons from the study include the importance of ensuring high levels of fidelity of the intervention. Furthermore, together with an increase in coverage, technological and social innovations are needed. It is also important that any intervention be situated within a collaborative care model that can help to detect and respond to women in need of other services to help social determinants, such as poverty and domestic violence, in addition to pharmacological interventions.
Because of the scarcity of specialists in many low-income and middle-income settings, task shifting for maternal depression is neccessary to bridge the treatment gap. Evidence-based, task-shifted, and targeted interventions for maternal depression and universal psychosocial interventions (eg, the Philani Maternal, Child Health, and Nutrition Project in South Africa) can be delivered through community health workers as well as lay peers.5, 6 However, most of these interventions are delivered either during pregnancy or in the early postnatal months, focusing on the acute phase of maternal depression, without tackling issues of recurrence and chronicity. To our knowledge, no depression interventions that begin prenatally are designed specifically to prevent recurrence after the perinatal period. Hence, the extent to which such interventions can break the cycle of recurrence of depression beyond the first postnatal year is unknown.
Although interventions have shown efficacious reductions in shorter term (ie, 12 months or less) maternal depression and improved maternal behaviours,7 whether such interventions can reduce intergenerational transmission to children is unknown. Many interventions for depression in the perinatal period include a child development component, opening the possibility that such interventions, including the Thinking Healthy Programme,8 could affect child outcomes through pathways that are independent of changes in depression symptoms themselves.5 Although maternal depression interventions have been shown to improve key parenting practices,9 evidence of the long-term effects on child socioemotional development is scarce.10 Studies showing improved child outcomes have short post-intervention follow-up periods, typically less than 12 months,11, 12, 13 leaving uncertainty about the potential outcomes of longer lasting programmes. The few studies that had follow-up durations of longer than 1 year have reported mixed or even incongruent effects.4, 6, 14, 15 For example, an analysis of the subset of women who were depressed when beginning the Philani+ programme in South Africa, which broadly focused on improving child outcomes and lasted through 6 months postnatally, showed improved child physical and cognitive outcomes at 18 months but higher levels of aggression at 5 years of age.6, 16 The challenges of differential attrition in longer-term follow-up periods, diminishing sample sizes, and heterogeneous responses in particular subgroups (eg, those exposed to poverty or intimate partner violence) make clear conclusions difficult.2, 15
The Thinking Healthy Program, Peer-delivered (THPP), delivers individual and group sessions from pregnancy to 6 months postnatal and has been evaluated through two randomised controlled trials, one in Pakistan and one in India.17, 18, 19 Although the country-specific findings were weak, the pooled analyses of these trials showed greater recovery from perinatal depression in the intervention group at 6 months postnatal. The individual trial in Pakistan also showed that delivering this psychosocial intervention through peers was a cost-effective, feasible, and acceptable approach.17
We evaluated a 36-month, task-shifted, psychosocial, peer-delivered intervention for maternal depression, Thinking Healthy Program, Peer-delivered Plus (THPP+),20 that followed up on the THPP. The project is located in rural Pakistan, a low-resource context characterised by high prevalence of maternal depression and little access to clinical mental health care.21
Although our hypothesis was that the children in the intervention group would be at less risk of having suboptimal developmental outcomes (compared with those in the control group), the full effect of the intervention can be discerned only if the amount of excess risk remaining (ie, the difference between the amount of risk in children of mothers with prenatal depression in the intervention group and the risk in children whose mothers did not have depression) is known. If the outcomes of these two groups are comparable, it can be inferred that the intervention is capable of preventing the intergenerational transmission of risk. To test the hypothesis, we therefore gathered data for women who did not have depression in pregnancy. These data for non-depressed women would allow us to compare outcomes in both mothers and children across the prenatally depressed groups versus the prenatally non-depressed group. The resulting pregnancy-birth cohort of women with prenatal depression (ie, trial participants) and women without prenatal depression was referred to as the Bachpan cohort (Bachpan means childhood in the local Urdu language). Finally, we examined whether intervention effects differ by key social contextual factors, such as socioeconomic status and intimate partner violence.
