Development, psychometric assessment, and predictive validity of a breastfeeding subjective norms scale among an Australian prospective cohort of first-time parents.

These findings indicate that the developed subjective norms scales are reliable and valid and capture key elements of breastfeeding subjective norms among both mothers and fathers. Use of this measure in future research can help better understand the role of both mothers' and fathers' subjective norms in influencing breastfeeding behaviours.