Maternal-foetal outcomes in pregnant women with glomerulonephritides. Are all glomerulonephritides alike in pregnancy?

In spite of the interest for chronic renal diseases (CKD) in pregnancy data on specific diseases is fragmentary; while recent studies analysed the most common glomerulonephritides (GN), none was addressed at GN as a group. The aim of our study was to analyse the main pregnancy-related outcomes in GN patients in a large multicentre cohort. Patients with a diagnosis of GN were selected from the TOCOS cohort (TOCOS: TOrino Cagliari Observational Study): out of 714 singleton deliveries GN was the diagnosis in 126; lupus GN and IgA nephropathy accounted for 37 and 33 cases; 1418 low-risk singleton deliveries followed-up in the same Centers served as controls (non diabetic, non nephropathic, non obese women, without any other known chronic illness; pregnancies after ovodonation or in vitro fertilisation were excluded, if declared). Multiple regression analysis considered: pre-term (<37 weeks), early preterm delivery (<34 weeks), small for gestational age baby (SGA) and the development of hypertension, proteinuria and preeclampsia (PE) limiting this outcome to the cases without hypertension and proteinuria at baseline. The population consisted mainly of early CKD stages (stage 1: 61.9%; hypertension 27.8%; proteinuria <0.5 g/day: 55.7%). Age and parity were not different in cases and low-risk controls (age: 31.20 ± 5.5 vs 31.24 ± 5.5 years, primiparous 56.3% vs 57.5%). The incidence of preterm and early preterm delivery was higher in GN versus controls and increased commensurately with CKD stage. In the multivariate analysis, CKD stage was significantly associated with early preterm delivery and development-doubling of proteinuria (odds ratio (OR) around 3 in both), while the OR for baseline hypertension did not reach statistical significance. While the risk pattern did not differ in lupus and non-lupus GN, a significantly higher OR of PE was observed in IgA nephropathy (OR 28.09 versus other GN); risk for pre-term delivery was not increased (OR 0.27 (0.06-1.11)), thereby suggesting "late-maternal" PE. In conclusion, within the limits of heterogeneity and small numbers, our analysis identifies proteinuria as the most reliable risk marker for adverse pregnancy outcomes and suggests a specific association between IgA nephropathy and late-maternal PE.