Adherence to Multiple Micronutrient Supplementation in Pregnancy: A Systematic Review Integrating HBM, TPB, and PRECEDE-PROCEED

In the 2018 national survey, almost half of pregnant women in Indonesia were anemic (48.9%), and the national program is shifting from iron-folic acid (IFA) to multiple micronutrient supplements (MMS). This study aims to synthesize evidence on determinants of MMS adherence among pregnant women through the Health Belief Model (HBM), the Theory of Planned Behavior (TPB), and the PRECEDE-PROCEED framework, and to describe how adherence levels are associated with maternal and neonatal outcomes. This study used a systematic review following PRISMA 2020 with narrative thematic synthesis. Nine databases and two organizational portals yielded 487 records; 27 were included, namely 16 evidence-contributing studies (one individual participant data [IPD] meta-analysis of 15 randomized trials with 61,204 women, two other systematic reviews/meta-analyses, one literature review, and 12 primary studies) and 11 supporting documents. Study quality was appraised with JBI, CASP, and AMSTAR-2 tools. In the IPD meta-analysis, MMS increased birth weight relative to IFA by 56 g (95% CI: 45–67) among women with ≥90% adherence, but by only 9 g (95% CI: −17 to 35) at <60% adherence. In observational analyses among MMS recipients, adherence <75% (versus 75–90%) was associated with a higher risk of maternal anemia (RR 1.26; 95% CI: 1.11–1.43) and stillbirth (RR 1.43; 95% CI: 1.12–1.83). Perceived benefits and perceived barriers were the most consistently reported psychological determinants, followed by self-efficacy and perceived behavioral control. Enabling factors (tablet availability, distance, cost, employment) and reinforcing factors (husband and family, cadres, midwives) shaped whether intention became consumption. Higher adherence is associated with better maternal and neonatal outcomes, and individual beliefs, perceived control, and the service and social environment jointly shape adherence.