Strengths and limitations
depression
This study has several strengths. The data are from a randomised trial. Using a post-hoc power analysis, the study sample size is adequately powered to detect a difference of 0.3 between the two groups in incidence of poor psychological outcomes at 90% power and an alpha value of 0.05; an effect size that is considered small using Cohen’s standardized effect size criteria [The main limitation of our study is that women who did not participate in our study (did not consent to completion of questionnaires on mental health) may differ from those who did with regards to the outcome (e.g., may have been suffering from poor mental health) which may result in a selection bias. Secondly, we used self-reported measures to assess mental health outcomes in our study which are not considered as diagnostic gold standards. The EPDS cut-off used in our study has, however, been reported as similar in accuracy to clinical interviews which are considered as the gold standard for diagnosis of depression during pregnancy and in the postpartum period [