Household member influence on women's willingness-to-pay for multiple micronutrient supplementation (MMS)

Last registered on June 17, 2026

Pre-Trial

Trial Information

General Information

Title
Household member influence on women's willingness-to-pay for multiple micronutrient supplementation (MMS)
RCT ID
AEARCTR-0018709
Initial registration date
June 10, 2026

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
June 17, 2026, 12:23 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

Region

Primary Investigator

Affiliation
UC Davis Agricultural & Resource Economics

Other Primary Investigator(s)

PI Affiliation
UC Davis ARE
PI Affiliation
UC Davis ARE

Additional Trial Information

Status
In development
Start date
2026-06-15
End date
2026-09-01
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Maternal and child health indicators in Senegal have shown limited progress in the past decades. The current standard prenatal supplement in Senegal, iron-folic acid (IFA), has been shown to decrease the incidence of low birthweight by as much as 21%, and neonatal mortality by 27%, relative to a control group when all 180 doses are taken (Srivastava et al., 2025). However, in 2019, just 66% of women in Senegal took at least 90 doses of IFA during their last pregnancy (Nutrition International, 2025). Maternal micronutrient supplementation (MMS) is now the WHO-recommended prenatal supplement, shown to have even better outcomes than IFA. However, as governments designate MMS as the standard of care, attention must be paid to boost demand such that MMS does not face the same insufficient demand as IFA. This study examines whether a prompted conversation with family members such as a husband or mother-in-law affects women's willingness-to-pay for MMS. Upon recruitment at a first antenatal care appointment, pregnant women will be randomized into a treatment group that receives a prompt and flyer that encourages them to discuss their valuation of MMS with a family member before the survey team returns. The survey team will return the next day for the Becker-de-Groot Marschak auction on MMS. If we find that this interaction increases a woman’s WTP for MMS relative to when women are not encouraged to talk to a family member, for example, then one action the government could take to increase demand would be to involve household members beyond the woman in purchasing decisions about MMS.
External Link(s)

Registration Citation

Citation
Lybbert, Travis , Stephen Vosti and Madeleine Walker. 2026. "Household member influence on women's willingness-to-pay for multiple micronutrient supplementation (MMS)." AEA RCT Registry. June 17. https://doi.org/10.1257/rct.18709-1.0
Experimental Details

Interventions

Intervention(s)
Upon recruitment at a first antenatal care appointment, pregnant women will be randomized into a treatment group that receives a prompt and flyer that encourages them to discuss their valuation of MMS with a family member before they participate in an MMS auction. The survey team will return to their home the next day for the Becker-de-Groot Marschak auction on MMS.
Intervention Start Date
2026-06-15
Intervention End Date
2026-09-01

Primary Outcomes

Primary Outcomes (end points)
Interaction with a household member between recruitment and survey team home visit, Women's willingness-to-pay for MMS
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
women's preferred size of MMS (30/60/90 tablet), WTP demand curves
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Midwives who recruit women for the MMS auction will vocally encourage a conversation with family members and give a flyer depicting this to every other woman recruited for the auction.
Experimental Design Details
Not available
Randomization Method
every other
Randomization Unit
individual woman
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
N/A
Sample size: planned number of observations
400 women
Sample size (or number of clusters) by treatment arms
N/A
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
28% minimum detectable effect in WTP in CFA; using SD = 1
IRB

Institutional Review Boards (IRBs)

IRB Name
University of California, Davis Institutional Review Board
IRB Approval Date
2026-06-01
IRB Approval Number
2392330-1