Amniotic fluid volume and pregnancy outcomes in twin pregnancies: A systematic review and meta-analysis

To analyse amniotic fluid volume (AFV), specifically oligohydramnios or polyhydramnios, and associated pregnancy and neonatal outcomes in twin gestations through systematic review and meta-analysis.

We utilised systematic review methodology to identify items within published and grey literature resources. Prospective and retrospective studies with a control group were included. Inclusion criteria were as follows: studies in English, twin pregnancy in which AFVs and associated pregnancy and/or neonatal outcomes were evaluated. Exclusion criteria included the presence of an anomalous fetus, chromosome abnormality, monochorionic diamniotic twin pregnancy complicated by twin-twin transfusion syndrome or twin-reversed arterial perfusion, twin gestations undergoing therapeutic interventions (i.e. fetoscopic laser photocoagulation and serial amniocentesis) and monochorionic monoamniotic twin pregnancy.

The literature search identified 1068 abstracts, only four met criteria for inclusion and analysis. The pooled data (two studies per outcome) revealed no significant difference in rate of pre-term delivery (OR: 2.94; CI: 0.20-43.81), pre-term delivery less than 32 weeks (OR: 1.97; CI: 0.43-9.12), umbilical cord pH < 7 (OR: 2.66; CI: 0.22-32.51), rate of stillbirth (OR: 4.13; CI: 0.40-42.70), neonatal death (OR: 1.48; CI: 0.05-43.94), rate of NICU admission (OR: 1.38; CI: 0.61-3.11) or rate of small-for-gestational-age (SGA) infants (OR: 1.39; CI: 0.33-5.94).

Based on the pooled data (two studies per outcome), there was no difference in the fate of pre-term delivery, umbilical cord pH < 7, stillbirth, neonatal death or SGA infants. What is disturbing is the lack of studies (1946-2020) that analysed the association between AFV and pregnancy outcomes in twin pregnancies.