Inclusion Criteria:  Confirmed pregnancy by ultrasound scanning or urine or serum beta-HCG Chronic kidney disease stage 1 to 5, defined as abnormalities of serum creatinine, urine constituents or renal tract anatomy for more than 3 months, or genetic traits associated with renal disease  Exclusion Criteria:  Known primary thrombophilia (including factor V Leiden, prothrombin mutations, protein C deficiency, protein S deficiency) Treatment with low molecular weight heparin in 24 hours prior to consent Suspected or confirmed active pre-eclampsia or superimposed pre-eclampsia