Preterm birth

Abstract

More than 70% of neonatal and infant morbidity and mortality occurs in infants born preterm. Spontaneous preterm birth is a syndrome in which the parturitional process may be initiated by one or more pathways culminating in cervical ripening, decidual activation, uterine contractions and ruptured membranes. Major risk factors for preterm birth are a history of previous preterm delivery and multifetal gestation, but most women who deliver preterm have no apparent risk factors. Every pregnancy is potentially at risk. Progesterone supplementation reduces the risk of preterm birth by about 40% in women with a singleton pregnancy who have had a previous spontaneous singleton preterm birth and in women with a short cervix on ultrasound examination in the current pregnancy. Other obstetrical interventions to reduce neonatal morbidity such as, antenatal glucocorticoids, tocolysis and antibiotics for group B streptococcal prophylaxis, are effective tertiary therapies but have no opportunity to reduce de incidence of preterm birth.