Phase 1 · Understand the Body — Why the disease behaves the way it does.
The One-Line Truth
The whole disease in one chain
Everything on this page exists to explain this line.
Blood pressure 140/90 or higher after 20 weeks of pregnancy with no protein in the urine and no organ damage.
Pregnancy as a City Water System Upgrade
Imagine a city that needs to triple its water supply to a new neighborhood (the baby). The water company must widen the old narrow pipes (spiral arteries) into fat, flexible hoses so 3× the flow can rush through without pressure spiking. In gestational high blood pressure (hypertension), the construction crew (trophoblast cells) stops early—the pipes stay narrow and rigid. The water gets through, but the pump (heart) has to work harder, so pressure climbs to 140/90 or higher. The pipe walls stay intact (no leaks, so no protein in urine), and the city's buildings don't flood (no organ damage yet). But because the supply line is choked, the neighborhood gets less water than it should, and the system is one bad day away from cracking.
ACOG Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia (2020) · American Heart Association / American College of Cardiology Hypertension in Pregnancy Guideline · CDC Pregnancy Complications: High Blood Pressure · U.S. Preventive Services Task Force (USPSTF) Preeclampsia Screening Recommendation · reviewed 2026-07-07