Pregnancy Hypercoagulability
Pregnancy shifts hemostasis toward clotting readiness well before delivery.
- ↑↑: Factor VIII / fibrinogen rise through gestation
- ↓: Protein S activity falls, removing a natural anticoagulant brake
- ↑: The gravid uterus compresses the pelvic veins, adding stasis
- 5x: Baseline VTE risk versus the non-pregnant state
Why pregnancy is prothrombotic
An evolutionary adaptation that limits bleeding at delivery also raises clot risk throughout gestation and the weeks after.
Cesarean Delivery Adds Thrombosis Risk
Surgery, vessel injury, and post-operative immobility compound the pregnancy baseline.
- 2-4x: Risk versus vaginal delivery
- Present: Direct vessel wall injury from surgery
- Hours: Typical post-op immobility window
- Higher: Emergency sections carry more risk than elective ones
Surgical contribution to Virchow's triad
Endothelial injury, stasis and hypercoagulability converge during and after a cesarean delivery.
Immobilization and Venous Stasis
Reduced calf-muscle pump activity slows venous return sharply after delivery.
- ↑ risk: Every extra hour of bed rest
- Inactive: Calf muscle pump while lying still
- ↑: Blood pooling at the valve pockets
- ↓↓: Flow velocity through the deep veins
Stasis as the clot nucleation trigger
Pooled blood near valve cusps is where a deep vein clot most often begins.
Age, Obesity and Compounding Risk
Additional factors stack on top of the baseline risk rather than simply adding to it.
- +risk: Maternal age over 35
- +risk: Obesity (BMI over 30)
- +risk: Prior VTE or known thrombophilia
- +risk: Multiple gestation (twins or more)
Cumulative risk scoring
Counting present risk factors guides real prophylaxis decisions in postpartum care.
Prevention — Ambulation, Compression, Anticoagulation
Early mobilization and compression stockings restore near-normal venous flow.
- Effective: Early ambulation after delivery
- Effective: Graduated compression stockings
- High risk cases: LMWH pharmacologic prophylaxis
- ~65%: Typical relative risk reduction with prophylaxis
Combining prophylaxis measures
Mechanical and pharmacologic prophylaxis together lower DVT incidence more than either alone.
Early walking after delivery is the simplest, most effective prevention available to almost every postpartum patient.