Appropriate antenatal corticosteroid use in women at risk for preterm birth before 34 weeks of gestation

Objective To determine the utilisation of antenatal corticosteroid administration in women presenting at risk of preterm birth (PTB) in a centre where tocolytics are not prescribed. Design A prospective cohort study. Setting Tertiary referral centre, Dublin, Ireland. Population Four hundred and fourteen consecutive women presenting at risk of PTB. Methods Clinical details were collated prospectively on all booked patients who presented at risk of PTB (i.e. at < 34 weeks of gestation) during 2008. Main outcome measure Rate of administration of antenatal corticosteroids in PTB. Results Of 8985 deliveries, 414 women (5%) presented at < 34 weeks of gestation with a clinical potential for PTB, of whom 277 (67%) received antenatal corticosteroids. Amongst women delivering at < 34 weeks of gestation, 93% (80/86) received any corticosteroids and 76% (65/86) received a complete course. The ratio of women given a complete course of corticosteroids to the number who actually delivered before 34 weeks of gestation was 4:1 overall. Analysis by indication for PTB revealed this ratio to be 15:1 in suspected preterm labour (PTL), 8:1 in antepartum haemorrhage (APH), and 2:1 in both preterm prelabour rupture of membranes (PPROM) and medically indicated PTB (MIPTB). Seven of ten multiparae (70%) who delivered prematurely during the study period following PTL had a history of previous PTL before 34 weeks of gestation. Conclusion The ratio of maternal antenatal corticosteroid administration for potential versus actual PTB at < 34 weeks of gestation was high in categories such as PTL and substantial APH, whereas selection in PPROM and MIPTB approached 100%. There should be a low threshold for single course therapy for women with prior PTL before 34 weeks of gestation.