|Source||Location and Type of Study||Intervention||Stillbirths/Perinatal Outcomes|
|Reviews and meta-analyses|
|Magann et al. 2007 ||
Systematic review. 7 studies included. N = 3 studies of idiopathic polyhydramnios, N = 4 studies of polyhydramnios that adjusted for congenital anomalies.
|Assessed the association of idiopathic polyhydramnios on perinatal outcomes.||PMR: 2-fold to 5-fold increase in risk in polyhydramnios vs. normal AFI groups, respectively.|
|Mazor et al. 1996 ||
Cohort study. Singleton pregnancies (N = 4211) with intact membranes and pre-term delivery (< 37 wks).
|Compared the effect in the group with increased amniotic fluid volume (exposed) vs. normal amniotic fluid volume (unexposed) by sonographic assessment.||
PMR: OR = 5.8 (95% CI: 3.68–9.11).|
Intrapartum morbidity: OR = 2.8 (95% CI: 1.94–4.03).
Polyhydramnios was an independent predictor of perinatal mortality and intrapartum morbidity.
|Dashe et al. 2002 ||
Retrospective cohort study. N = 672 singleton pregnancies with hydramnios categorised as mild, moderate, or severe based on greatest amniotic fluid index of 25.0-29.9 cm, 30.0-34.9 cm, or 35.0 cm or more, respectively.
|To characterise the prevalence and ultrasound detection of fetal anomalies in pregnancies with hydramnios, and to estimate anomaly and aneuploidy risks when no sonographic abnormality is noted.||
77 (11%) of neonates had one or more anomalies.|
Fetal death rate: 4%; 60%; of these had anomalies.
|Erez et al. 2005 ||
Retrospective logistic regression analysis. N = 192 SGA neonates with polyhydramnios, N = 5,515 SGA neonates with normal amniotic fluid, N = 3,714 appropriate for gestational age (AGA) neonates with polyhydramnios, N = 83,763 AGA.
|Assessed the impact of combined SGA and polyhydramnios on perinatal mortality.||PMR: OR = 20.55 (95% CI: 12.6–33.4) comparing SGA+polyhydramnios to AGA fetuses with normal AFI|
|Shoham et al. 2001 ||
Matched case-control study. N = 368 women with gestational diabetes mellitus (N = 194 with polyhydramnios, AFI>25 cm; N = 184 women with normal AFI) under strict metabolic control enrolled from 1995–1996.
|To determine whether gestational diabetes (GDM) complicated with hydramnios is associated with higher rates of perinatal morbidity and mortality than those with normal amniotic fluid (AFI).||No significant differences in rates of antepartum fetal death.|