The Effect of Two Aspirin Dosing Strategies for Obese Women at High Risk for Preeclampsia

The Effect of 81mg vs 162mg ASA for Preeclampsia Prevention in Obese Women at High Risk for Developing Preeclampsia

Low dose aspirin (LDA) is used for preeclampsia (PE) prevention in high risk women, but the precise mechanism and optimal dose is not known. Evidence in the non-obstetric literature suggests AR may be more common among patients with a high body mass index (BMI). Recent unpublished data showed that LDA substantially lowers TxB2 levels regardless of BMI, but rates of complete platelet inhibition are lower in women with BMI ≥40. This data suggests that higher doses of ASA may be necessary in obese women. Therefore we plan determine if use of 162mg compared to the traditional 81mg ASA decreased rates of preeclampsia in women considered high risk for developing preclampsia.

Evidence suggests that an imbalance in prostacyclin and thromboxane A2 (TxA2) plays a key role in PE. Aspirin (ASA) has a dose-dependent effect blocking production of TxA2, a potent stimulator of platelet aggregation (PA) and promoter of vasoconstriction. Incomplete inhibition of PA, designated aspirin resistance (AR), can be reduced by increasing the ASA dose.

Inclusion Criteria:

• BMI at enrollment >/= 30
• plan for ASA for preeclampsia prevention

Exclusion Criteria:

• BMI < 30
• already on ASA