Dietary diversity as a modifier of the effect of supplementation with multiple micronutrients during pregnancy on low birth weight in a randomized controlled trial in Bangladesh

Mary de Boer; Andrew L Thorne-Lyman; Abu Ahmed Shamim; Lee Wu; Saijuddin Shaikh; Hasmot Ali; Keith P West Jr; Parul Christian

doi:10.1016/j.ajcnut.2025.07.007

Dietary diversity as a modifier of the effect of supplementation with multiple micronutrients during pregnancy on low birth weight in a randomized controlled trial in Bangladesh

Am J Clin Nutr. 2025 Jul 11:S0002-9165(25)00396-X. doi: 10.1016/j.ajcnut.2025.07.007. Online ahead of print.

Authors

Mary de Boer¹, Andrew L Thorne-Lyman², Abu Ahmed Shamim³, Lee Wu², Saijuddin Shaikh⁴, Hasmot Ali⁴, Keith P West Jr², Parul Christian²

Affiliations

¹ Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA. Electronic address: mdeboer5@jh.edu.
² Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA.
³ Center for Noncommunicable Diseases and Nutrition, BRAC James P Grant of School of Public Health, BRAC University, Mohakhali, Dhaka, Bangladesh.
⁴ The JiVitA Project, Johns Hopkins Bloomberg School of Public Health, Rangpur, Bangladesh.

PMID: 40653272
DOI: 10.1016/j.ajcnut.2025.07.007

Abstract

Background: Meta-analysis of trials of multiple micronutrient supplements (MMS) vs iron-folic acid (IFA) suggests an overall benefit of 12% on low birthweight (LBW).

Objective: Building on prior work showing that MMS is more effective in anemic and higher BMI females, this paper explores whether dietary quality modifies the effect of MMS on birthweight.

Methods: A seven-day food frequency questionnaire was administered in late pregnancy to 19,160 pregnant participants in the JiVitA-3 cluster-randomized controlled trial of MMS vs. IFA supplementation in Bangladesh. A 10-item dietary diversity score (DDS) was created summing the number of food groups consumed ≥4 times/week. Risk ratios (RR) and 95% confidence intervals (CI) for the effect of MMS vs IFA on LBW were estimated by DDS. The interaction between DDS and MMS was tested using a generalized estimating equations log-binomial regression model to account for the cluster randomization. Point estimates and 95% CI for the effect of MMS on LBW were estimated at each DDS. Models were adjusted for confounders. We used p < 0.1 to determine statistical significance of the interaction.

Results: The median DDS was 3 (IQR: 2-4), and 18.6% of PW had a score ≥ 5. The fully adjusted protective effect of MMS on LBW was inversely associated with dietary diversity [MMSxDDS RR: 1.02 (95% CI: 1.00, 1.04), p-interaction = 0.05]. The effect was greatest at the lowest DDS [DDS= 1, RR LBW: 0.86 (0.81, 0.91)] and decreased at higher scores [DDS = 7, RR: 0.92 (0.84, 1.00)].

Conclusions: In rural Bangladesh, where maternal dietary diversity was generally low, MMS (compared to IFA) supplementation had the strongest effect on reducing low birth weight among pregnant females with the least diverse diet, possibly reflecting the additional benefit of supplementation in this vulnerable group.

Gov identifier: NCT00860470.

Associated data

ClinicalTrials.gov/NCT00860470