Abstract
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 individualized 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, biomarkes). 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.
Financial & competing interest disclosure
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
Key issues
• 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.
• Systematic reviews have shown that test accuracy for predicting preterm birth overall is disappointing.
• The risk indicators and indicators for preterm labour can be categorized in five groups; characteristics of the individual (ethnicity/race), fetal characteristics (fetal gender, fetal number and chorionicity) obstetric history (history of preterm birth), modifiable risk indicators (social status, BMI, infection) and signs of early labor; potential predictors (sonographic markers and biomarkers).
• Black ethnicity/race, fetal male gender are seen as risk indicators for preterm birth, one should realize, risk assessments are based on traditional definitions of preterm birth, in other words, delivery before 37 weeks, and that those curves of normalcy are made on populations with in majority of Caucasian women. So it is important to take into account individual biological pathways.
• Infection and socio-economic status are modifiable risk indicators for preterm birth.
• Shortening of the cervix and the presence of fetal fibronectin has been shown to be predictive of preterm birth. These indicators where seen as risk indicator but can actually be seen as first symptoms of preterm birth.
• Studies of biomarkers have improved the understanding of the mechanisms of disease leading to spontaneous preterm birth, but so far only fetal fibronectin has shown clinical usefulness.
• Previously described models for predicting preterm birth, are not ready for actual implementation in current patient care.
• Even with the implementation of seemingly valid interventions only little progress is made, in reducing the number of preterm births.
• The way forward includes improved individualized classification for the causes of preterm birth, allowing for early diagnosis and better risk stratification, followed by development of new preventive interventions based on understanding of the underlying etiology.