| Factor | Effect on Nasal Passages | |--------|--------------------------| | | Increases blood volume and vasodilation; promotes glandular hyperactivity and mucus secretion. | | Progesterone | Causes vascular smooth muscle relaxation, leading to engorgement of nasal venous sinuses. | | Placental Growth Hormone | Enhances nasal mucosal blood flow. | | Increased Blood Volume | Up to 50% increase by third trimester → nasal mucosa congestion. |