Low-dose aspirin (60–150 mg/day) started before 16 weeks gestation reduces the risk of pre-eclampsia primarily by which mechanism?
- A Blocking placental sFlt-1 production and restoring angiogenic balance
- B Irreversibly inhibiting platelet cyclooxygenase-1, thereby reducing thromboxane A2 ✓
- C Inhibiting uterine natural killer cell activity at the implantation site
- D Reducing maternal fibrinogen levels and blood viscosity
Correct answer: B. Irreversibly inhibiting platelet cyclooxygenase-1, thereby reducing thromboxane A2
Explanation
Low-dose aspirin irreversibly acetylates platelet COX-1, preferentially inhibiting thromboxane A2 synthesis (a vasoconstrictor and platelet aggregator) over prostacyclin. This shifts the thromboxane/prostacyclin balance toward vasodilation and reduced platelet aggregation, improving placental perfusion. sFlt-1 is an anti-angiogenic biomarker but aspirin does not directly block its production.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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