Management of Threatened Preterm Birth without Premature Rupture of the Membranes

The frequency of preterm birth has increased markedly during the past two decades. Preterm births are responsible for more than 75% of all neonatal deaths. There is general agreement that expectative management is recommended between the 24th and 34th weeks of gestation to reduce neonatal morbidity and mortality. Tocolytic therapy with beta-agonists, atosiban or calcium channel blockers succeeds in prolonging pregnancy for at least 48 hours in 90% of cases; however, sufficient data is not available to date which would confirm the efficacy of maintenance tocolysis. The primary aims of tocolytic therapy are to allow the administration of a complete course of antepartal glucocorticosteroids in order to achieve foetal lung maturation and to arrange in utero transfer to a specialised perinatal centre. There is good evidence suggesting that antenatal application of glucocorticosteroids, mainly betamethasone, leads to a significant reduction in neonatal morbidity and mortality. At present, repeat close(s) of glucocorticosteroids cannot be recommended for routine practice. The prophylactic administration of antibiotics is not indicated in cases of threatened preterm labour without rupture of the membranes. Symptomatic bacterial infections, such as bacterial vaginosis, should be treated as early as possible during pregnancy. Commonly used strategies such as bed rest, hydration or sedation are not evidence-based measures. Cervical cerclage is still a matter of debate in the current literature. An elective cerclage should be offered to patients with a history of :3 unexplained midtrimester pregnancy losses or preterm deliveries. Midtrimester transvaginal ultrasonography to measure the cervical length is an effective way of identifying pregnant women at high risk for preterm birth. Therapeutic cerclage in patients with previous second trimester abortions/preterm birth(s) and presenting a cervical length < 2.5 cm significantly reduces the risk of later preterm birth and non-significantly the rate of perinatal mortality. Recent studies have confirmed the beneficial effect of progesterone to prevent recurrent preterm birth (vaginal progesterone 100 mg daily or 250 mg of 17-alpha-hydroxyprogesterone caproate weekly). The efficacy of prophylactic progesterone application in different high-risk populations is currently under investigation.