What causes sudden nosebleeds in a pregnant woman who is over seven months pregnant?

A pregnant woman at over seven months gestation suddenly experiencing nosebleeds is usually due to elevated progesterone levels, vitamin C deficiency, or similar causes. Excessive secretion of progesterone during pregnancy leads to dilation of capillaries throughout the skin and mucous membranes, resulting in congestion of the skin and mucous membranes and an increased blood volume compared to the non-pregnant state. The nasal mucosa contains abundant blood vessels with thin walls, making them prone to rupture and bleeding. Vitamin C deficiency increases capillary fragility, which may lead to symptoms such as nosebleeds and requires prompt treatment. Severe vitamin C deficiency may also cause oral ulcers or bleeding in other parts of the body.