Iron deficiency during pregnancy prevents normal heart recovery postpartum and may contribute to peripartum cardiomyopathy, according to combined mouse and human studies. In iron-deficient mice, pregnancy-induced heart enlargement failed to reverse after delivery, ejection fraction decreased, and heart muscle showed severe iron depletion. Among 64 women without heart failure, those with low iron markers showed reduced heart function and higher cardiac imaging signals indicating iron deficiency at 6-12 months postpartum. A separate case-control study of 225 women found significantly lower iron levels in those who developed peripartum cardiomyopathy. The research identifies a specific metabolic pathway—activation of pyruvate dehydrogenase kinase 4—as a potential mechanism linking iron deficiency to heart dysfunction. This enzyme acts as a metabolic switch associated with heart failure development. The findings suggest iron deficiency, which affects up to 40% of pregnant women globally, may be an underrecognized risk factor for postpartum cardiac complications. However, as this preprint awaits peer review, these results require validation. The research represents a potentially significant advance in understanding pregnancy-related heart disease, though clinical recommendations await further study.