Metabolic Syndrome and the Effectiveness of Low-dose Aspirin on Reproductive Outcomes

Metabolic syndrome is associated with increases in both inflammation and aspirin resistance, but effectiveness of aspirin in improving reproductive health among women with metabolic syndrome is unknown. We evaluated the effectiveness of low-dose aspirin in improving reproductive outcomes across metabolic syndrome score.

The EAGeR trial randomly assigned 1228 women with a history of pregnancy loss to receive 81 mg aspirin or placebo for up to six menstrual cycles of attempting pregnancy and, if they became pregnant, throughout pregnancy. We assessed components of metabolic syndrome at enrollment, including: waist circumference ≥88 cm, triglycerides ≥150 mg/dl, high-density lipoprotein ≤50 mg/dl, blood pressure ≥130 mmHg systolic or ≥85 mmHg diastolic, and glucose ≥100 mg/dl. We summed components to calculate metabolic syndrome score.

A total of 229 participants (20%) met full criteria for metabolic syndrome, 207 (18%) had two components, 366 (31%) one component, and 372 (32%) no components. Among those without any component of metabolic syndrome, aspirin was associated with 10.7 [95% confidence interval (CI) = 1.2, 20.2] more pregnancies and 13.7 (95% CI = 3.3, 24.0) more live births per 100 couples. Effects were attenuated as metabolic syndrome score increased and we observed no clear effect of aspirin on pregnancy or live birth among women with metabolic syndrome.

Low-dose aspirin is most effective in increasing pregnancy and live birth among women with no or few components of metabolic syndrome. Reduced effectiveness among women with metabolic syndrome may be due to differences in effective dose or aspirin resistance.