Association of Low-Protein Supplemented Diets with Fetal Growth in Pregnant Women with CKD

Abstract

Women affected by CKD increasingly choose to get pregnant. Experience with low-protein diets is limited. The aim of this study was to review results obtained from pregnant women with CKD on supplemented vegan-vegetarian low-protein diets. This was a single-arm, open intervention study between 2000-2012 of a low-protein diet in pregnant patients with stages 3-5 CKD or severe proteinuria (>1 g/d in the first trimester or nephrotic at any time). Stages 3-5 CKD patients who were not on low-protein diets for clinical, psychologic, or logistic reasons served as controls. The setting was the Obstetrics-Nephrology Unit dedicated to kidney diseases in pregnancy. The treated group included 24 pregnancies--21 singleton deliveries, 1 twin pregnancy, 1 abortion, and 1 miscarriage. Additionally, there were 21 controls (16 singleton deliveries, 5 miscarriages). The diet was a vegan-vegetarian low-protein diet (0.6-0.8 g/kg per day) with keto-acid supplementation and 1-3 protein-unrestricted meals allowed per week. Treated patients and controls were comparable at baseline for median age (35 versus 34 years), referral week (7 versus 8), eGFR (59 versus 54 ml/min), and hypertension (43.5% versus 33.3%); median proteinuria was higher in patients on the low-protein diet (1.96 [0.1-6.3] versus 0.3 [0.1-2.0] g/d; P<0.001). No significant differences were observed in singletons with regard to gestational week (34 versus 36) or Caesarean sections (76.2% versus 50%). Kidney function at delivery was not different, but proteinuria was higher in the diet group. Incidence of small for gestational age babies was significantly lower in the diet group (3/21) versus controls (7/16; chi-squared test; P=0.05). Throughout follow-up (6 months to 10 years), hospitalization rates and prevalence of children below the third percentile were similar in both groups. Vegan-vegetarian supplemented low-protein diets in pregnant women with stages 3-5 CKD may reduce the likelihood of small for gestational age babies without detrimental effects on kidney function or proteinuria in the mother.