Effect of pregnancy on renal function in patients with moderate-to-severe diabetic renal insufficiency

OBJECTIVE - Previous studies of patients with diabetic nephropathy and mild renal impairment have suggested no deterioration in renal function as a result of pregnancy. The objective of this study was to determine whether pregnancy may permanently worsen renal function in women with diabetic nephropathy and moderate-to-severe renal insufficiency. RESEARCH DESIGN AND METHODS - Eleven patients were identified with diabetic nephropathy and moderate-to-severe renal dysfunction (creatinine [Cr] greater than or equal to 124 mu mol/l [1.4 mg/dl]) at pregnancy onset by retrospective chart review. Alterations in glomerular filtration rate were estimated by using linear regression of the reciprocal of Cr over time. An equal number of nonpregnant premenopausal type I diabetic women with similar degrees of renal dysfunction served as a comparison group for nonpregnant rate of decline of renal function and potential contributing factors. RESULTS - Mean serum Cr rose from 159 mu mol/l (1.8 mg/dl) prepregnancy to 221 mu mol/l (2.5 mg/dl) in the third trimester. Renal function was stable in 27%, showed transient worsening in pregnancy in 27%, and demonstrated a permanent decline in 45%, Proteinuria increased in pregnancy in 79%. Exacerbation of hypertension or preeclampsia occurred in 73%. Seven patients progressed to dialysis 6-57 months postpartum, with 71% (five of seven) of these cases attributed to acceleration of disease during the pregnancy. Student's t tests and repeated-measures analysis of variance support a pregnancy-induced acceleration in the rate of decline of renal function. CONCLUSIONS - In this series, patients with diabetic nephropathy and moderate-to-severe renal insufficiency were found to have a >40% chance of accelerated progression of their disease as a result of pregnancy.