1. The effect of women’s parity (nulliparity versus multiparity)
2. The effect of the intervention provider (professional-based
versus lay-based)
3. The effect of the place where the interventions are provided
(specific location (e.g., hospital, home) versus by telephone)
4. Types of the intervention (one type of the interventions
versus the other)
5. Number of sessions of the intervention (single session
versus multiple sessions)
Only the primary outcome will be included in the subgroup analyses.
We will assess subgroup differences using interaction tests
available within RevMan (RevMan 2014). We will report the results
of subgroup analyses quoting the 2 statistic and P value,
and the interaction test I² value.