Results
Overall, 52 studies were included in this meta-analysis (references presented in the Appendix ). A summary of their methodological characteristics is presented in the Appendix . Most of the studies included pregnant women at the third trimester of pregnancy. The actual gestational age at assessment was particularly heterogeneous as several studies included populations at gestational ages that covered both the early and late preterm period. The Newcastle - Ottawa revealed that the methodological quality of included studies ranged from moderate to inferior. The quality of evidence following evaluation of the GRADE framework revealed moderate study limitations and significant inconsistency (Table 1 ).