Preterm Labor: Understanding of the Mechanism Involved to Improve Prediction and Prevention

Preterm birth is a significant problem occurring in around 10% of all deliveries and its increase is remarkable, even in developed countries. Being born under 37 weeks, and most importantly under 32 weeks, is the major cause of perinatal morbidity and mortality and accounts for the majority of neonatal deaths. Recent advances in perinatology and neonatology have increased survival rates, particularly for the extremely preterm baby. The associated morbidity for these survivors' remains significant, and up to one-quarter will have at least one major disability. This special issue focused in some aspect of the physiopathology of the preterm labor and different strategies to predict the patient at risk in order to improve the prevention of this pathology. This issue highlights the diversity of the physiopathology of preterm labor by including different points of view, such as focusing in the expression of steroid receptor coactivators in fetal membranes and its relationship with preterm labor. Using immunohistochemistry, western blot analysis, and real-time PCR, they demonstrate that SRC-1, SCR-2, p300, and PCAF proteins are present in nuclear extracts and display tissue-specific and labor-associated differential expression. In another paper, the authors propose a novel putative target for the prevention of infection-triggered preterm labor. They suggest that uterotonic effects of endothelin-1 (E-1) are mediated via sphingosine kinase (SphK). E-1 is a molecule that exerts potent oxytocic effects and is elevated in amniotic fluid obtained from preterm births. SphK plays a key role in ET-1-induced myometrial contractions and may represent a potential target for tocolysis to prevent preterm birth. In terms of prediction, a review accessing the accuracy of transvaginal sonographic cervical length in predicting preterm birth in women with twin pregnancy and symptoms of preterm birth is presented. The authors present a meta-analysis, using bivariate regression analysis, accounting for correlation between sensitivity and specificity. Despite the large variation in definition of preterm birth and cutoff point of cervical length and gestational age, they concluded that there is insufficient evidence to recommend the measurement of cervical length as a predictor of preterm birth in women with a twin pregnancy and symptoms of preterm birth because specificity and sensibility are low. With respect to prevention of preterm birth, a systematic review of the use of cervical pessaries and adjunctive therapies to cerclage is presented. The aim of one study was to evaluate the effective use of the cervical pessary to prevent preterm birth before 28, 34, and …