Risk of fetal death in growth-restricted fetuses with umbilical and/or ductus venosus absent or reversed end-diastolic velocities before 34 weeks of gestation: a systematic review and meta-analysis

OBJECTIVE: The objective of the study was to establish the risk of fetal death in early-onset growth-restricted fetuses with absent or reversed end-diastolic velocities in the umbilical artery or ductus venosus. DATA SOURCES: A systematic search was performed to identify relevant studies published in English, Spanish, French, Italian, or German using the databases PubMed, ISI Web of Science, and SCOPUS, without publication time restrictions. STUDY ELIGIBILITY CRITERIA: The study criteria included observational cohort studies and randomized controlled trials of early-onset growth-restricted fetuses (diagnosed before 34 weeks of gestation), with information on the rate of fetal death occurring before 34 weeks of gestation and absent or reversed end-diastolic velocities in the umbilical artery and/or ductus venosus. STUDY APPRAISAL AND SYNTHESIS METHODS: For quality assessment, 2 reviewers independently assessed the risk of bias using the Newcastle-Ottawa Scale for observational studies and the Cochrane Collaboration's tool for randomized trials. For the meta-analysis, odds ratio for both fixed and random-effects models (weighting by inverse of variance) were used. Heterogeneity between studies was assessed using tau(2), chi(2) (Cochrane Q), and I-2 statistics. Publication bias was assessed by a funnel plot for meta analyses and quantified by the Egger method. RESULTS: A total of 31 studies were included in this meta-analysis. The odds ratios for fetal death (random-effects models) were 3.59 (95% confidence interval, 2.3-5.6), 7.27 (95% confidence interval, 4.6-11.4), and 11.6 (95% confidence interval, 6.3-19.7) for growth-restricted fetuses with umbilical artery absent end-diastolic velocities, umbilical artery reversed end-diastolic velocities, and ductus venosus absent or reversed end-diastolic velocities, respectively. There was no substantial heterogeneity among studies for any of the analyses. CONCLUSION: Early-onset growth-restricted fetuses with either umbilical artery or ductus venosus absent or reserved end-diastolic velocities are at a substantially increased risk for fetal death.