Study design and sample size
We conducted a cross-sectional community-based study from
April-September 2016. Based on the study population size of
approximately 460 (husbands in 21 urban slums whose wife had childbirth
within one year), assuming that 50% of the husbands are involved in
BPCR (an optimal prevalence to get maximum sample size), assuming a
design effect of 1.5 (due to multi-stage random sampling), and an
expected 90% response rate, this study required 214 eligible husbands
for estimating the expected proportion with 15% precision relative to
the expected proportion and 95% confidence.
Sampling : Fig 1 summarises the multi-stage random sampling
method.
Selection of slums: Firstly, based on the slum size and eligibility for
various health schemes, we stratified 21 urban slums as large (with ≥100
households), small (<100 households) and designated Scheduled
Caste/Scheduled Tribe (SC/ST) slums. According to this stratification,
there were four large, nine small and eight designated SC/ST slums.
Secondly, considering the resource constraints, we selected 10 urban
slums (two large, four small, and four designated SC/ST slums) by simple
random sampling with proportional allocation in each category.
Selection of participants: In each of the selected slums, we obtained a
list of women who delivered within one year from the Anganwadicentres. The Anganwadi centre is the Integrated Child Development
Services (ICDS) scheme’s basic functional unit, which provides
supplementary nutrition, non-formal education, and health services to
under-five children. We decided the required number of women from each
slum by proportional allocation and selected by simple random sampling
from the slum wise list of women. None of the randomly selected women
was a widow, divorced or separated. We approached the husband of the
selected woman in the slum in the afternoon or early evening to ensure
their availability and better participation.