Stage 1 chronic kidney disease in pregnancy.

Stage 1 chronic kidney disease (CKD) is defined by normal renal function, an estimated glomerular filtration rate of >90 mL/minute and abnormalities on urinalysis or ultrasound. These patients when pregnant are commonly seen, and diagnoses include diabetic nephropathy, glomerulonephritis, nephrolithiasis, reflux nephropathy, polycystic kidney disease and lupus nephritis. Underlying renal disease may also first become apparent in pregnancy, posing a diagnostic challenge. Patients tend to do well, but all need to be closely monitored particularly for hypertension and pre-eclampsia, which are more common in patients with stage 1 CKD overall. Relevant pregnancy outcomes may be divided into maternal (e.g. renal deterioration, nephrolithiasis, lupus flare, urinary infection or pyelonephritis), fetal (e.g. growth restriction, fetal death or stillbirth) and obstetric (e.g. hypertension, pre-eclampsia, preterm delivery, thrombosis). Specific diagnoses, their clinical features, management strategies and prognosis are reviewed.