Objective To estimate the short term effect of the publication of a major clinical trial on clinical practise.

Design Questionnaire survey of clinical practise.

Setting UK.

Population All maternity units in the UK.

Method A self-administered questionnaire completed by lead consultants on delivery suite of maternity units.

Main outcome measures Changes in antibiotic prescription.

Results Within six months of publication, approximately 50% of maternity units had changed their guidelines for the care of women with preterm prelabour rupture of the fetal membranes.

Conclusion Publication of a major clinical trial does impact on clinical practise but the impact is heterogeneous in terms of time and consistency.