Retention of participants
In the period between enrolment into the study and the follow-up dental examination the number of participants declined. First, there were two rounds of exclusions imposed by the researchers. The first exclusion was based on information from medical records after the child’s birth. Women who had a miscarriage, intrauterine death or an infant with developmental defects (cleft ⁄ lip palate) were excluded from the study. The second exclusion process occurred when inviting participants to present their child for a dental examination. The reasons for exclusion at this point were death of the child (cot death, accidental death), or inability of mothers to care for the child (e.g. mother missing, arrested, sick, living in a safety house). In total, 24 subjects (15 in the test and nine in the control group) were lost to the study through exclusions.
Further losses to the study were categorized as ‘nonattendance’ (mother contacted, but unable or unwilling to bring the child for dental examination), ‘moved’ (mother moved to distant location), ‘loss’ (unable to locate). Figure 1 summarizes the flow of the participants through the key stages of the study.