Hypertension during Pregnancy: Causes

Pathogenesis (disease development)

The exact pathophysiologic processes of hypertensive disorders in pregnancy have not been fully elucidated. Several hypotheses have been developed that have three mechanisms in common:

1. Vessels are thought to be prone to vasospasm (vascular spasm)
2. In addition, there is likely to be an immunological component, as these disorders are most common in first-time mothers
3. In addition, there is a disturbed relationship between prostaglandins and thromboxanes (substances that are found in all human tissues and perform multiple tasks).

In preeclampsia, it has been demonstrated that the immune protein CD74 of the placenta is reduced and certain inflammatory factors are increased in affected pregnant women. There is a disruption of macrophage-trophoblast interaction. This, in turn, leads to disruption of the placenta‘s structure and undersupply of the fetus (embryo from the third month of pregnancy).

Etiology (causes)

Biographic causes

• Genetic burden from parents, grandparents (especially the angiotensinogen gene-T235)Heritability (inheritability) affects not only the mother but also the father and thus the fetus, which receives half of its genes:
  • Gene variants “rs476963” and “rs2050029” (on chromosome 13 near the FLT1 gene) → increased release of sFlt-1 causes damage to blood vessels and kidneys.
  • Trisomies (excess presence of one chromosome).
• Ethnic origin – women of color (African American) and women of Indian origin.
• Age – > 35 years or < 15 years.
• Current pregnancy: first-time parity, multiple pregnancy.
• Socioeconomic factors
  • Low socioeconomic status
  • Unmarried pregnant women
  • Working pregnant women

Behavioral causes

• Nutrition
  • Micronutrient deficiency (vital substances) – see Prevention with micronutrients.
• Overweight (BMI ≥ 25; obesity) – with obesity from a BMI of 35 quadruples the risk.

Disease-related causes

• Antiphospholipid syndrome – disease characterized by multiple concurrent thromboses; thromboses occur at a young age.
• Bladder mole – malformation of the placenta (placenta), which is considered precancerous (precancerous).
• Chronic hypertension (high blood pressure).
• Diabetes mellitus
• Factor V mutation – genetic blood clotting disorder that leads to an increased tendency to thrombosis.
• Gestational diabetes (gestational diabetes).
• Hydrops fetalis – most severe form of blood group incompatibility between mother and child, which leads to death in the child.
• Hypertension (high blood pressure), chronic.
• Systemic lupus erythematosus (SLE) – systemic disease affecting the skin and connective tissue of the vessels, leading to vasculitides (vascular inflammation) of numerous organs such as the heart, kidneys or brain.
• Thrombophilia – increased tendency to thrombosis due to changes in the blood and / or vessels.
• Trisomy – numerical chromosomal aberration in which there is a set of chromosomes increased by one.
• Pre-existing kidney disease

Other causes

• Renewed pregnancy with new partner
• First pregnancy
• Multiple pregnancy
• Condition following hypertensive encephalopathy of pregnancy (HES) – condition n. hypertension in a previous pregnancy.
• Condition after undergone preeclampsia in a previous pregnancy.

Environmental exposure – intoxications (poisonings).

• Air pollutants: particulate matter (PM2.5) and nitrogen oxides.