Inclusion Criteria:  Confirmed pregnancy Gestational age < 12+0 weeks Live fetus at time of booking ultrasound scan (between 11+0 and 13+6 weeks of gestation) To be considered as high risk of preeclampsia  Exclusion Criteria:  Age under 18 years Hyperemesis gravidarum Unable to sign the consent form Type 1 or 2 diabetes mellitus Early gestational diabetes Auto-immune disease Fetal abnormality identified at time of scanning (between 11+0 and 13+6 weeks of gestation) Bleeding disorder Peptic ulcer Hypersensitivity to aspirin or metformin Long use of NSAIDS before initiation of intervention Contraindication to metformin or aspirin and participation in another concurrent trial.