Preterm delivery: an overview

Preterm delivery is the leading factor causing neonatal mortality and morbidity. We have conducted a PubMed literature search to obtain an update on the etiology, diagnostic problems and therapeutic considerations of preterm delivery. Approximately 5-10% of all births are premature. Preterm labor is associated with preterm rupture of membranes, cervical incompetence, polyhydramnion, fetal and uterine anomalies, infections, social factors, stress, smoking, heavy work and other risk factors. The diagnosis is made on the patients presenting symptoms, clinical findings and of progressive effacement and dilatation of the cervix. Biochemical markers of preterm delivery are of minor importance in daily clinical work. Measurement of the cervix, however, is a practical and valuable tool to predict preterm delivery. Cervical cerclage can be useful in selected cases. Antibiotics may help to prevent preterm labor in cases of known etiologic agents (e.g. preterm rupture of membranes and urinary infection). The use of tocolytic agents such as beta-sympathetic receptor stimulators can be advocated for a few days. There is evidence that their long-term use is not beneficial and could even be harmful to the fetus. Calcium channel blockers (nifedipine) and a new selective oxytocin receptor antagonist, atosiban, appear to be as effective as beta-sympathomimetic drugs on uterine contractions with fewer side-effects. Prostaglandin synthetase inhibitors such as indomethacin may prevent uterine contractions and can be used prior to the 32nd week of pregnancy. A single course of corticosteroid treatment in two doses of 12 mg betamethasone or 6 mg of dexamethasone is important for the prevention of respiratory distress between the 24th and 34th weeks of pregnancy. Multiple doses may be harmful and should be avoided. In these cases management should depend on gestation age (fetal maturity). Uterine contractions after 34 weeks' gestation are not an indication for tocolytic treatment.