A randomised trial of timed delivery for the compromised preterm fetus: short term outcomes and Bayesian interpretation The GRIT Study Group * Participants are listed at the end of this article Objectives To compare the effect of delivering early to pre-empt terminal hypoxaemia with delaying for as long as possible to increase maturity. Design A randomised controlled trial. Setting 69 hospitals in 13 European countries. Participants Pregnant women with fetal compromise between 24 and 36 weeks, an umbilical artery Doppler waveform recorded and clinical uncertainty whether immediate delivery was indicated. Methods The interventions were ‘immediate delivery’ or ‘delay until the obstetrician is no longer uncertain’. The data monitoring and analysis were Bayesian. Main outcome measures ‘Survival to hospital discharge’ and ‘developmental quotient at two years of age’, this latter to be reported later. Results Of 548 women (588 babies) recruited, outcomes were available on 547 mothers (587 babies). The median time-to-delivery intervals were 0.9 days in the immediate group and 4.9 days in the delay group. Total deaths prior to discharge were 29 (10%) in the immediate group versus 27 (9%) in the delay group (odds ratio 1.1, 95% CI 0.61 – 1.8). Total caesarean sections were 249 (91%) in the immediate group versus 217 (79%) in the delay group: (OR 2.7; 95% CI 1.6–4.5). These odds ratios were similar for those randomised at gestational ages above or below 30 weeks. Interpretation The lack of difference in overall mortality suggests that clinicians participating in this trial were on average prepared to randomise at about the correct equivocal threshold between delivery and delay. However, there was insufficient evidence to convince enthusiasts for either immediate or delayed delivery that they were wrong. Introduction Obstetricians use many tests of fetal wellbeing to predict fetal death and handicap 1 . In high risk pregnancy, use of the umbilical artery Doppler flow-velocity waveform may reduce perinatal mortality 2 . However, the only realistic intervention in most cases is delivery, and there is little information as to when to do this. Data sets relating clinical outcome to gestational age 3 and to the degree of test abnormality 4 are of limited help because they include a heterogeneous group of pregnancies with delivery timing unspecified. It is not surprising that policies vary widely 5,6 . Delay may increase hypoxia and affect brain development 7 , but early delivery carries the dangers of prematurity and the associated risk of cerebral palsy. The Growth Restriction Intervention Trial (GRIT) was designed to help time delivery for such babies. The aim was to compare the effect of delivering them early, to pre-empt intrauterine hypoxia, with the effect of delaying delivery for as long as possible, in order to gain maturity. The entry criteria were flexible as the degree of abnormality that would make obstetricians consider delivery varied with gestational age and between doctors 8 . Two risk factors were specified a priori, gestational age and the degree of abnormality of the umbilical artery end-diastolic flow- velocity waveform (EDF). Methods The criteria for entry were singleton or multiple preg- nancies where the responsible clinician was uncertain whether to deliver the baby immediately, the gestational age was between 24 and 36 weeks and the umbilical artery Doppler waveform had been recorded. Basic clinical data, the umbilical artery Doppler waveform and, if available, the results of a biophysical profile score, computerised CTG analysis and cerebral artery Doppler waveform were recorded pre-randomisation. An experimental Internet randomisation programme was used for one participant 9 . A paper-based number sequence with balanced blocks of 8–12 was used except during office hours when a com- puter-generated sequence was used. This latter minimised on the following variables: centre (UK teaching hospital, BJOG: an International Journal of Obstetrics and Gynaecology January 2003, Vol. 110, pp. 27–32 D RCOG 2003 BJOG: an International Journal of Obstetrics and Gynaecology PII:S1470-0328(02)02514-4 www.bjog-elsevier.com * Correspondence: Professor J. G. Thornton, Division of Obstetrics and Gynaecology, City Hospital, Nottingham NG5 1PB, UK.