The Aspirin We All Prescribe, But Rarely Get Right:
Low-dose aspirin for preeclampsia prevention has been around for decades, yet Dr. Ajay Singh argues we still get the dose, timing, and duration wrong - and shares a case where history-based risk missed what combined screening caught.
A Drug We've Had for Decades, Still Used Inconsistently: The drug itself isn't new -it's been around seventy-plus years, since early research linked a poorly invaded placenta to preeclampsia and IUGR. What's striking, says Dr. Ajay Singh, a senior consultant in high-risk obstetrics for over a decade, is how inconsistently we still use it: "there are many different prescriptions out in the OPD... some medicines where we have not optimized the dose properly." The biology is simple -defective trophoblastic invasion leaves the placenta underperfused, tipping the thromboxane–prostacyclin balance toward vasoconstriction. Low-dose aspirin irreversibly blocks thromboxane while sparing prostacyclin, restoring balance.
Who Actually Qualifies: One high-risk factor -prior preeclampsia, multifetal pregnancy, chronic hypertension, diabetes, renal or autoimmune disease -justifies starting aspirin outright; moderate factors (nulliparity, BMI over 30, age 35+, a long interpregnancy interval, prior low-birth-weight baby, or ART conception) need two or more. One grey area many miss: hypothyroidism, not universally scored as autoimmune, but which he counts as one. The FOGSI-ICOG gestosis score combines these - a score of three or higher means high risk, triggering aspirin plus daily calcium before 16 weeks.
The Dose and Timing That Actually Work: Guideline doses diverge (81mg to 150mg across ACOG, RCOG, WHO, FIGO), but pooled trial data - twenty studies, 12,500 participants - favors at least 100mg daily for reliable platelet inhibition without added bleeding risk, started before 16 weeks, while spiral-artery remodeling is underway. Start later, and benefit drops sharply.
Why Bedtime Beats Morning: One easily-overlooked, evidence-backed detail: platelet reactivity and renin-angiotensin activity both peak on waking, so bedtime dosing blunts that surge and gives better blood pressure control than morning dosing - now standard in major trial protocols.
How Long to Continue, and What to Watch For: Continue daily through at least 36 weeks or until delivery - no need to stop for spotting, or hold before cesarean or regional anesthesia. Contraindications: allergy, active GI bleeding, bleeding disorders, hepatic impairment; asthma needs caution, not avoidance.
The Case That Makes the Point: A 22-year-old primigravida, BMI 22, low risk by history. But her uterine artery PI sat at the 18th centile, flagging biophysical-only risk at 1:90. She initially refused aspirin, swayed by a relative's bad experience; combined biochemical screening then recalculated her risk at 1:120, bridging history and scan.
The Takeaway: No single guideline fits every patient - combining history, biophysical, and biochemical screening is clinically sound and medicolegally defensible. As he put it: don't be afraid to start aspirin early, and don't blame it for bleeding it rarely causes.