Perinatal Outcomes of Idiopathic Polyhydramnios with Normal Ultrasound: A Systematic Review and Meta-Analysis

Background: Incidence of polyhydramnios in various studies has been reported from 0.2 to 3.9%. Approximately, 50-60% of cases are idiopathic with no known etiology. We aimed to investigate perinatal outcomes of idiopathic polyhydramnios with a normal ultrasound. Materials and Methods: In this study, Persian and English databases including Barakatkns, SID, Magiran, Medline, Science Direct, Scopus, Cochran, Embase, and ProQuest were searched for articles published from 1950 to August 2018. The search procedure was conducted with keywords related to "idiopathic polyhydramnios", "perinatal outcomes", "normal ultrasound", and their equivalents in "Mesh" and PICO. In meta-analysis, first we quantified heterogeneity by using I2 statistics and tested using the Cochran’s Q test. Even when a low heterogeneity was detected, a fixed-effects model was applied, and for more than 75% of heterogeneity, random-effects model was used. The Forest Plot chart was drawn up and the relative risk (RR) estimate for each study (ES), the pooled estimate of "RR" by combining all the studies and its 95% CI, and the P-value associated with it, were indicated. Results: In this study, 13 articles involving 325,426 pregnant women were included for the Meta-analysis. The RR and 95% CI of Caesarian Section (C.S), 1.61(1.25-2.07), macrosomia, 1.84(1.40-2.42), preterm delivery, 2.45(1.29-4.64), NICU admission, 2.90(1.77-4.74), Apgar score min 5