Pregnancy in dialysis patients in the new millennium: a systematic review and meta-regression analysis correlating dialysis schedules and pregnancy outcomes

Advances have been made in the management of pregnancies in women receiving dialysis; however, single-centre studies and small numbers of cases have so far precluded a clear definition of the relationship between dialysis schedules and pregnancy outcomes. The aim of the present systematic review was to analyse the relationship between dialysis schedule and pregnancy outcomes in pregnancies in chronic dialysis in the new millennium. Medline-PubMed, Embase and the Cochrane library were searched (1 January 2000-31 December 2014: MESH, Emtree, free terms on pregnancy and dialysis). A separate analysis was performed for case series (more than five cases) and case reports. Meta-regression was performed in case series dealing with the larger subset of haemodialysis (HD) patients; case reports were analysed separately [according to peritoneal dialysis (PD) versus HD; conception before or during dialysis]. We obtained 190 full texts and 25 congress abstracts from 2048 references. We selected 101 full papers and 25 abstracts (36 series; 90 case reports), for a total of 681 pregnancies in 647 patients. In the case series (574 pregnancies in 543 patients), preterm delivery was extremely frequent (83%). Meta-regression analysis showed a relationship between hours of dialysis per week in HD and preterm delivery, and was significant for preterm deliveries (< 37 gestational weeks: P = 0.044; r(2) = 0.22) and for small for gestational age (SGA) (P = 0.017; r(2) = 0.54). SGA was closely associated with the number of dialysis sessions per week (P = 0.003; r(2) = 0.84). Case report analysis suggests a lower incidence of SGA on HD versus PD (31 versus 66.7%; P = 0.015). No evidence of an increased risk of congenital abnormality was found in the retrieved papers. Data on pregnancy on dialysis are heterogeneous but rapidly accumulating; the main determinant of outcomes on HD is the dialysis schedule. The differences between PD and HD should be further analysed.