Background: Placental insufficiency results in chronic fetal hypoxemia and progressive cardiovascular adaptation that may culminate in myocardial dysfunction. Conventional fetal surveillance relies primarily on arterial Doppler parameters, which reflect placental resistance and fetal circulatory redistribution but do not directly assess cardiac performance. Pulmonary vein Doppler reflects left atrial pressure and ventricular compliance and has emerged as a potential marker of fetal diastolic dysfunction. Objective: To systematically review contemporary evidence on the role of pulmonary vein Doppler in pregnancies complicated by placental insufficiency and intrauterine growth restriction (IUGR), focusing on fetal cardiac dysfunction and perinatal outcomes. Methods: A systematic literature search was conducted in PubMed, Scopus, and Embase for studies published between January 2019 and June 2025. Studies assessing pulmonary vein Doppler parameters in pregnancies complicated by placental insufficiency or IUGR were included. Study selection followed PRISMA 2020 guidelines. Risk of bias was assessed using the Newcastle–Ottawa Scale. Results: Twelve studies met inclusion criteria. Pulmonary vein pulsatility index (PVPI) was consistently elevated in growth-restricted fetuses compared with appropriately grown fetuses. Elevated PVPI was associated with fetal diastolic dysfunction, abnormal arterial Doppler indices, and adverse perinatal outcomes including neonatal intensive care unit admission and neonatal acidosis. In several studies, pulmonary vein Doppler abnormalities preceded deterioration in arterial Doppler parameters. Conclusion: Pulmonary vein Doppler is a sensitive marker of fetal cardiac diastolic dysfunction in placental insufficiency. Its integration into comprehensive fetal surveillance protocols may improve early detection of fetal compromise and support more individualized clinical decision-making.