This study presents a novel intravital imaging platform for studying placental development and function in mice. The researchers developed an implantable placenta window that allows high-resolution photoacoustic and fluorescence imaging throughout pregnancy. This window is optically and acoustically transparent, enabling longitudinal imaging of the placenta without the need for repeated surgeries. The platform, combined with ultrafast functional photoacoustic microscopy (UFF-PAM), provides detailed spatiotemporal information on placental hemodynamics and molecular activities. Key findings include: 1. **Placental Development**: UFF-PAM images show that placental vessel diameter increases by 200% from early to mid-pregnancy due to spiral artery remodeling, and vessel density increases monotonically until the second trimester. Oxygenation (sO2) levels initially decrease to promote angiogenesis but then increase to meet fetal demands. 2. **Alcohol Consumption**: Alcohol consumption induces rapid hyperperfusion and elevated sO2 levels, potentially causing oxidative stress and neurological damage to the fetus. 3. **Cardiac Arrest (CA)**: CA causes immediate and substantial reduction in sO2, leading to vasodilation and increased vessel diameter. The placenta compensates by dilating vessels, but prolonged hypoxia may cause long-term damage. 4. **Inflammation**: LPS-induced inflammation reduces microvessel density and increases sO2 levels, disrupting the normal hypoxic environment that promotes placental development. 5. **Viral Gene Delivery and Chemical Diffusion**: The placenta window enables tracking of viral gene delivery and chemical diffusion, providing insights into transport mechanisms and therapeutic applications. The study demonstrates the potential of this intravital imaging platform for understanding placental functions and developing treatments for pregnancy complications.This study presents a novel intravital imaging platform for studying placental development and function in mice. The researchers developed an implantable placenta window that allows high-resolution photoacoustic and fluorescence imaging throughout pregnancy. This window is optically and acoustically transparent, enabling longitudinal imaging of the placenta without the need for repeated surgeries. The platform, combined with ultrafast functional photoacoustic microscopy (UFF-PAM), provides detailed spatiotemporal information on placental hemodynamics and molecular activities. Key findings include: 1. **Placental Development**: UFF-PAM images show that placental vessel diameter increases by 200% from early to mid-pregnancy due to spiral artery remodeling, and vessel density increases monotonically until the second trimester. Oxygenation (sO2) levels initially decrease to promote angiogenesis but then increase to meet fetal demands. 2. **Alcohol Consumption**: Alcohol consumption induces rapid hyperperfusion and elevated sO2 levels, potentially causing oxidative stress and neurological damage to the fetus. 3. **Cardiac Arrest (CA)**: CA causes immediate and substantial reduction in sO2, leading to vasodilation and increased vessel diameter. The placenta compensates by dilating vessels, but prolonged hypoxia may cause long-term damage. 4. **Inflammation**: LPS-induced inflammation reduces microvessel density and increases sO2 levels, disrupting the normal hypoxic environment that promotes placental development. 5. **Viral Gene Delivery and Chemical Diffusion**: The placenta window enables tracking of viral gene delivery and chemical diffusion, providing insights into transport mechanisms and therapeutic applications. The study demonstrates the potential of this intravital imaging platform for understanding placental functions and developing treatments for pregnancy complications.