Practice patterns in the timing of antenatal corticosteroids for fetal lung maturity.

OBJECTIVE: To determine the practice patterns of antenatal corticosteroid (AS) administration in women with threatened preterm labor.

METHODS: This was a retrospective cohort of patients who received betamethasone between 2009 and 2010, identified through a pharmacy database. Patients with high order multiples; incomplete records and indicated preterm delivery were excluded. Demographic and obstetrical factors were compared between women with an AS to delivery latency of ≤7 days versus >7 days. Parametric and non-parametric tests were used as appropriate. p < 0.05 denotes statistical significance; relative risks with 95% confidence intervals were calculated.

RESULTS: Three-hundred forty-five patients were included. Sixty-eight patients (20%) received AS within 7 days of delivery. Women who received AS ≤7 days before delivery (optimal timing) were more likely to have a transvaginal cervical length ≤2 cm (RR:2.53, CI: 1.2-5.6), cervical dilation ≥2 cm (RR: 3.86, CI: 2.7-5.6) and positive fFN (RR: 2.59, CI: 1.1-6.3). Preterm premature ruptured membranes were also associated with optimal timing of AS (RR: 4.86, CI: 3.4-6.8).

CONCLUSIONS: Eighty percent of patients receive suboptimal timing of AS administration. Factors associated with suboptimal timing are: cervical length >2 cm, cervical dilation <2 cm and negative fFN. Cervical assessment should be a key factor in the decision for AS administration. More research is needed for accurate timing of AS in women with threatened preterm labor.