Multiple micronutrient supplementation (MMS) during pregnancy offers greater benefits for pregnancy outcomes and early infant growth than iron and folic acid supplementation (IFA), although both are used as preventive antenatal care interventions. Several low- and middle-income countries (LMICs) have begun introducing MMS. However, concerns about higher costs have slowed wider adoption. This study examined what would happen if 25 LMICs with the highest burden of low birthweight replaced preventive IFA supplements with MMS under different costing and coverage scenarios. The researchers found that switching from IFA to MMS would not only prevent millions of adverse birth outcomes over five years but also generate substantial economic benefits, with returns at least ten times the cost. These findings provide a compelling case for LMICs to transition from preventive IFA to MMS.