Behavioural nudges and maternal diet: Results from a cluster-randomised pilot trial among pregnant women in India

Micronutrient shortfalls pose a significant threat to maternal health across India. We evaluate whether brief, low-intensity informational nudges can improve short-run maternal diet quality during pregnancy. We conducted a pilot cluster-randomised controlled trial across 22 primary health centre (PHC) catchments in Karnataka, assigning catchments to one of three behavioural interventions (printed pamphlets, Accredited Social Health Activist (ASHA) home visits, or research-team phone calls) or to routine-care control. A panel of 440 pregnant women was surveyed at baseline and again four weeks later. Primary outcomes were small meal frequency and two 24-hour dietary diversity measures: a continuous score and the binary Minimum Dietary Diversity for Women. Using multi-arm difference-in-differences models with pooled specifications, we find modest improvements over time across all arms. However, the interventions did not improve meal frequency or dietary diversity relative to the control group. These inferences were robust to 100 control-group subsampling iterations. Over this four week pilot period, low intensity, information only nudges did not improve meal frequency or dietary diversity beyond standard care by policy relevant amounts, helping bound the short run impacts of brief informational messaging in this setting.