Reflux nephropathy and the risk of preeclampsia and of other adverse pregnancy-related outcomes: a systematic review and meta-analysis of case series and reports in the new millennium.

BACKGROUND

Reflux nephropathy is a common urinary tract malformation, and a substantial cause of morbidity in women of childbearing age. While recent studies provide further new information on pregnancy-related outcomes, their results are heterogeneous and a systematic meta-analysis may help the interpretation. The aim of this review was to analyze pregnancy-related outcomes in the recent literature on reflux nephropathy (2000-2016), to perfect the estimation of risks, and to identify specific research needs.

METHODS

We searched Medline, EMBASE and the Cochrane review databases for the period 2000-2016 (PROSPERO registration no. 42016042713).

SELECTION CRITERIA

all case series and case reports dealing with reflux nephropathy and reporting on at least one pregnancy outcome. Data were extracted from eligible case series (≥ 6 cases). For the outcomes preeclampsia (PE), pregnancy-induced hypertension (PIH), preterm birth, and newborns small for gestational age, we employed as a control group the low-risk pregnancies from a multicenter database including 1418 live-born singletons. Case reports were analyzed narratively.

RESULTS

The search retrieved 2507 papers, of which 7 case series and 4 case reports were retained. The series report on 434 women with 879 pregnancies; no study reported controls. Compared to the low-risk controls, the meta-analysis showed an increased risk of PIH (odds ratio, OR 5.55; confidence interval, CI 3.56-8.66), PE (OR 6.04; CI 2.41-15.13), and all hypertensive disorders combined (OR 10.43; CI 6.90-15.75). No difference was observed in preterm delivery and caesarean sections. A higher incidence of stillbirth was reported in one paper. Conversely, the 4 case reports (on 10 pregnancies) alert us to a potentially severe complication, hydro(uretero)nephrosis with or without infection.

CONCLUSION

Reflux nephropathy is associated with an increased risk of PIH and PE, but not of preterm delivery, suggesting the occurrence of late 'maternal' PE. The finding of a higher incidence of stillbirths in one series requires further analysis. Strict follow-up of these women is needed, in particular in late pregnancy stages, to avoid and manage in particular hypertensive pregnancy complications.