Introduction

Chronic kidney disease (CKD) is relatively common and therefore, in women of childbearing age, is likely to be a common cause of secondary hypertension. In the nonpregnant state, CKD is defined either as kidney damage (which is confirmed by renal biopsy or secondary markers of damage) or the presence of a glomerular filtration rate (GFR) of less than 60 ml/minute/1.73 m2 for a period of greater than 3 months. It is likely that the prevalence of CKD will increase in general terms within the UK, with the introduction of the estimated GFR (eGFR) and that, with the ageing population of women embarking on pregnancy, this increase will be disproportionate amongst women pregnant for the first time. Recent data collected from the USA indicate that approximately 5% of the overall population suffers from reduced GFR (less than 60 ml/minute/1.73 m2). Chronic kidney disease is strongly associated with hypertension and the greater the severity of renal impairment the higher the risk. In end-stage renal disease, 80% of patients have associated hypertension.

The prevalence of hypertension varies somewhat with the aetiology of the underlying disease, with approximately 40% prevalence in chronic interstitial nephritis, immunoglobulin A (IgA) nephropathy and minimal change disease in the nonpregnant population, whereas rates of above 60% are associated with diabetic nephropathy, adult-type polycystic renal disease and focal segmental glomerulosclerosis. Interestingly, in the end-stage renal disease patient, systolic hypertension is more common than combined systolic and diastolic hypertension.