For stepped-wedge cluster randomized trial (Burkina Faso)
To estimate the sample size for the randomized staggered-corner cluster design, the country team used one of the main indicators, that is, the proportion of pregnant women who made the first contact before 12 weeks of pregnancy. The current estimate for this indicator is approximately 40%. In total, the sample size is 1600 women per period on the basis of the following assumptions:80% powerAn ICC of 0.1Detect a ‘true’ proportion difference of 10%.The team will need 1600 women per period. Accounting for missing data, the team will increase the size of the sample by 20%, which brings us to a minimum of 1920 women per period, or 960 women to be surveyed per region. For each study period, we will have 1920 (60 women × 4 health facilities × 4 districts × 2 regions) or 240 women per health district. The total sample for Burkina Faso will be 11 520 women who come for ANC.In both countries, data from 30 pregnant women who seek ANC for the first time either at the selected health facility (or in its catchment area) will be abstracted from the ANC registers during each month (see Table 