[Prevention of preterm birth complications by antenatal corticosteroid administration].

OBJECTIVE: To evaluate short- and long-term benefits and risks associated with antenatal administration of a single course of corticosteroids and the related strategies: multiple and rescue courses.

METHODS: The PubMed database, the Cochrane Library and the recommendations from the French and foreign obstetrical societies or colleges have been consulted.

RESULTS: Antenatal administration of a single course of corticosteroids before 34 weeks of gestation is associated in the neonatal period with a significant reduction of respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC) and death (LE1), and in possibly childhood with a reduction of cerebral palsy and increased psychomotor development index and intact survival (LE3). However, this treatment is associated with alterations of the HPA axis response persisting until 8 weeks after birth (LE2) and possibly with insulin resistance in adulthood (LE3). Antenatal corticosteroid administration after 34 weeks is associated, with high number needed to treat, with reduced respiratory morbidity (LE2), with no significant effect on neurological (LE2) or digestive (LE2) morbidities. Because of a very favourable benefit/risk balance, antenatal administration of a single course of corticosteroids is recommended for women at risk of preterm delivery before 34 weeks (grade A). The minimum gestational age for treatment will depend on the threshold chosen to start neonatal intensive care in maternity units and perinatal networks (Professional consensus). After 34 weeks, evidences are not consistent enough to recommend systematic antenatal corticosteroid treatment (grade B), however, a course might be indicated in the clinical situations associated with the higher risk of "severe" RDS, mainly in case of planned cesarean delivery (gradeC). In case of imminent preterm birth, pre-empting the second betamethasone injection is not recommended (gradeC), because this policy might be associated with increased rates of NEC (LE3). Repeated antenatal corticosteroid administration is associated in the neonatal period with respiratory benefits (LE1) but decreased birth weight (LE1) and, in childhood, with possible neurological impairment (LE2). Therefore, this strategy is not recommended (grade A). Rescue courses are only associated with neonatal respiratory benefits (LE2). Because of the possible adverse effects associated with this strategy when delivery occurs during the 24hours following the first injection and because of the doubts raised by repeated courses, rescue courses are not recommended (Professional consensus). It is not possible to recommend one corticosteroid (betamethasone or dexamethasone) over another (Professional consensus). In case of contraindication for the intramuscular (IM) route, the intravenous route might be proposed (Professional consensus). The oral route is not recommended (grade A) because of increased rates of IVH and neonatal sepsis in comparison with the IM route (LE1). Either betamethasone as 2 injections of 12mg 24hours apart or dexamethasone as 4 injections of 6mg 12hours apart is recommended (grade A). Antenatal corticosteroid-induced alterations of fetal heart rate and movements should be recognized by the care providers of women at risk of preterm birth to avoid unjustified decision of labor induction or cesarean (Professional consensus). Gestational diabetes and pre-existing diabetes are not contraindication to antenatal corticosteroid therapy (Professional consensus). However, caution should be exercised in women with poorly controlled type 1 diabetes (Professional consensus). The apprehension to provoke maternal or neonatal infection should not delay antenatal corticosteroid administration even in case of preterm premature rupture of membranes (grade A).

CONCLUSION: Antenatal corticosteroid administration is recommended to every woman at risk of preterm delivery before 34 weeks of gestation (grade A). Repeated courses of antenatal corticosteroids are not recommended (grade A). Rescue courses are not recommended (Professional consensus).