Doctors are often uncertain whether to deliver a small premature baby, or to continue observation in the uterus. Handicap and death may result from either course and there are no unbiased data to inform borderline decisions, so policies vary widely. Randomised controlled trials are required, and since November 1994 the UK Medical Research Council has been funding the pilot phase of one, the Growth Restriction Intervention Trial (GRIT). This is a pragmatic trial with clinician uncertainty (equipoise) as the main entry criterion. The primary outcome measures are survival and developmental quotient at two years of age, and analysis will be stratified by both the gestational age at entry and the degree of abnormality of the umbilical artery Doppler flow velocity waveform. The recruitment target in the UK was 900 subjects over 5 years, but recruitment has been slow because clinician equipoise has been less common than was anticipated. A number of European centres have expressed interest in joining GRIT and we propose to link them in a Concerted Action. This will increase recruitment. It will also increase generalisability, since thresholds for delivery vary around Europe. During the concertation we will also collect the results of automated analysis of CTG variability before randomisation. This will facilitate recruitment for clinicians presently managing patients this way and permit stratification for analysis based on this variable. The main Concertation target is the recruitment of 250 subjects to GRIT over three years.