Prediction of spontaneous preterm birth: no good test for predicting a spontaneous preterm birth.

PURPOSE OF REVIEW: Spontaneous preterm birth complicates 3-11% of pregnancies and is a major cause of neonatal mortality and morbidity worldwide. If accurate tests can be identified, a potentially effective screening strategy with an adjunct preventive therapy may be trialled to reduce the rate of spontaneous preterm birth or effective measures be deployed at an early stage of a suspected spontaneous preterm labour before the onset of cervical changes to ameliorate prematurity complications.

RECENT FINDINGS: There are many tests predicting spontaneous preterm births, published in the literature individually or in a systematic review. The information has not been collated about all candidate tests simultaneously in a systematic review incorporating a framework on how these tests may be evaluated, modelled with an intervention to provide a number needed to treat and test to inform decision-making.

SUMMARY: There were 319 studies evaluating 22 tests. There are many promising tests, for example, history of previous spontaneous preterm birth, cervicovaginal swabs for markers such as fibronectin or HCG, cervical ultrasound, serum CRP and amniotic fluid interleukins for predicting spontaneous preterm birth, but none have exceptional accuracy and the quality of studies was generally poor. Some tests were able to achieve high LR+, but at the expense of LR-, that is, tests good for ruling in disease were poor for ruling out disease and vice versa.