Table 2 Sample size estimates by study aim

Study aim 1a*

Face to face survey to measure changes in infant feeding practices

Women 5–7 months pregnant in four districts of MP

5000

• 5% change in reported practice of immediate and exclusive breastfeeding

• Loss to follow-up of 20% from enrolment to final follow-up visit

• Variance inflation factor of 1.25

Study aim 1b

Phone survey to measure changes in infant feeding

Postpartum women randomized to Kilkari

5000

Descriptive survey; administered to all women enrolled into the study

Study aim 1c*

Test-retest

Women 5–7 months pregnant in four districts of MP

168 women to be interviewed twice

• Proportion of positive responses of 0.35 for rater 1 and 0.40 for rater 2

• Adjusting for a 15% loss to follow-up/refusal between the first and second surveys

Study aim 1*

Phone survey for postpartum women: infant feeding, essential newborn care, RMC during childbirth

Women 1–4 months postpartum in two districts of MP

880 women interviewed as part of face to face surveys contacted to yield 146 completed face to face and phone survey interviews

• 20% phone survey response rate

• Proportion of positive responses of 0.35 for rater 1 and 0.40 for rater 2

Study aim 2*

Phone survey for pregnant women: RMC during pregnancy

Women 5–7 months pregnant in four districts of MP

880 women interviewed as part of face to face surveys contacted to yield 146 completed face to face and phone survey interviews

• 20% phone survey response rate

• Proportion of positive responses of 0.35 for rater 1 and 0.40 for rater 2

Study aim 2

MCTS/RCH registration

• FLHWs

• Block and district medical officers

• Data entry officers

Study aim 4

User perceptions of Kilkari

• FLHWs: ASHAs, ANMs

• Women enrolled to Kilkari and male phone owners