Figure 1. Sample selection procedure for evaluation of the effect of women’s groups on postpartum psychological distress.

From 25,615 births and deaths (‘events’) over the 24 study months in 2010 and 2011 we excluded data from: 17,181 events that did not occur within the SRQ-20 data collection periods; 62 events where it was not possible to conduct an interview due to migration or refusal; 1945 events associated with mothers who were temporary residents in the study area; nine events associated with a maternal death; 100 events associated with mothers who had previously delivered during the SRQ-20 data collection periods, either because of multiple births or through repeated births; 23 mothers due to missing SRQ-20 data. In total, 6275 mothers were included in the final sample.