Individualizing the risk for preterm birth; an overview of the literature

Preterm birth is the most important cause of perinatal morbidity and mortality worldwide and ranks among the top 10 of global causes of burden of disease. Since treatment of threatened preterm delivery has limited effectiveness, the focus is on primary and secondary prevention. Identification of risk indicators in early pregnancy provides the opportunity for preventive measures. To determine the potential impact of individualised risk indicators on the prediction of preterm birth, we reviewed the literature on this topic. Risk indicators for spontaneous preterm birth can be categorized in five groups; characteristics of the individual (ethnicity/race), characteristics of the fetus (fetal gender, fetal number and chorionicity), obstetric history (history of preterm birth), modifiable risk indicators (social status, life style, infection), and signs of early labour; potential predictors (sonographic markers, biomarkers). Risk for preterm birth can be seen as a continuous transition from one state to the other. The number of studies that integrate these data is limited.