The pathological changes in patients with hypertension during pregnancy are as follows: 1. Systemic small-vessel spasm: including the brain, kidney, liver vessels, and even affecting the limb vessels. Small-vessel spasm can lead to disorders in the ascending and descending systems of patients, and the vascular wall is sensitive to ascending substances with increased reactivity, which aggravates systemic small-vessel spasm and leads to an always sufficient effective circulating blood volume, or even overload, and further increase in blood pressure; 2. Water and sodium retention: as the glomerular filtration rate of patients decreases, it leads to increased sodium reabsorption by the renal tubules, resulting in edema to increase body weight, while adrenocorticotropic hormone and anti increased secretion of diuretic hormone, which aggravates water and sodium retention.