Controversies in diagnosis of preterm labour.

Despite scientific advances, efforts to prevent preterm birth can be disappointing. Obstetric care must focus on strategies to improve the outcome of preterm infants. The major goal is to delay preterm birth long enough to allow the transfer of women about to deliver preterm to a facility with a neonatal intensive care unit and to administer corticosteroids to enhance fetal lung maturation. A prerequisite for the success of this strategy is the reliable identification of women who will give birth preterm. Although symptoms of preterm labour strongly suggest preterm birth, contractions-even if combined with cervical effacement and dilation-do not reliably predict preterm birth. The diagnosis of true preterm labour that will eventually lead to preterm birth has been facilitated by the use of transvaginal cervical ultrasonography and by the detection of fetal fibronectin (FFN) in cervicovaginal secretions. The main clinical value of these tests is that preterm birth is very unlikely if the results of both tests are negative. This may help to avoid unnecessary transfer, hospitalisation and treatment of women with false preterm labour. The detection of phosphorylated insulin-like growth factor binding protein-1 in cervicovaginal secretions, or elevated levels of inflammatory markers, like interleukin-6, interleukin-8 and tumour necrosis factor-alpha (TNF-alpha), also predict preterm birth in symptomatic women. These markers, however, are not routinely used to predict preterm birth in women with symptoms of preterm labour.