The objective of this paper is to characterise and quantify the association between vaginal bleeding and pregnancy outcome. A meta-analysis was performed in order to quantify the risk of adverse reproductive outcome by combining evidence from all previous studies of vaginal bleeding. The reproductive endpoints considered were low birthweight, preterm birth, stillbirth, perinatal death and congenital malformation. The meta-analysis confirms an association of vaginal bleeding with adverse pregnancy outcomes, but identified discrepancies in the reported risks of vaginal bleeding and magnitudes of association between bleeding and adverse reproductive outcomes, observed across studies. These discrepancies may be attributed to inconsistent definitions of the timing and severity of vaginal bleeding. The implications of such inconsistencies are discussed, suggesting a need for more standardised definitions of vaginal bleeding and reproductive endpoints in future studies.