Discussion
SECONDARY
Using data from the MCH-ART study, which showed that integrated maternal and child health care during the postpartum period significantly increased retention in HIV care and viral suppression [Taken together, the intervention appeared to be most effective among women experiencing added vulnerability due to poverty, unintended pregnancy, and HIV-related stigma. We have previously demonstrated that unintended pregnancy is associated with elevated VL during the postpartum period [Our finding regarding alcohol use is of particular concern. In South Africa, alcohol use during pregnancy is a major public health problem. High levels of problematic alcohol use have been observed among women living both with and without HIV in this setting [In this secondary analysis, we observed no single definitive mediator of the intervention effect. We hypothesise that the intervention may be effective through a range of mechanisms that may operate differently within different groups of women, and should be explored in a larger trial. For example, integrated MCH services reduce the economic burden of attending separate visits and may thus be of most benefit to women experiencing higher levels of poverty [These findings should be considered in light of several limitations. They arise from a single antenatal clinic in a peri-urban area of South Africa and only women who were initiating ART during pregnancy were enrolled into the trial, thus the findings may not be generalisable to all postpartum women living with HIV. Although all postpartum women may benefit from integrated HIV and MCH care, only breastfeeding women were enrolled into the trial, thus limiting generalisability. Pregnant women were enrolled into the trial between March 2013 and April 2014 and were followed through January 2016, and changes in PMTCT and HIV care since that time may make our findings less generalisable to the current context. The psychosocial constructs explored were self-reported and are subject to recall and social desirability bias, which may be particularly relevant for behaviours such as alcohol use, although we used validated scales wherever possible. However, it is plausible that we did not observe hypothesised mediators of the intervention effect due to the challenges of measuring complex constructs, with the measures administered potentially not accurately representing the construct of interest. Although these measures were originally developed several decades ago in high-income countries, the constructs assessed and items included in these scales are still relevant and applicable to multiple settings. Although we attempted to collect patient-level data on direct and indirect costs to measure the economic burden of attending clinic visits, these data were only available for a subset of participants and it was not possible to accurately quantify costs at the individual level [