To guide future practice, perinatal trials should be much larger, simpler and less fragile with close to 100% ascertainment of mortality and other key outcomes

The Australian Placental Transfusion Study (APTS) randomised 1,634 fetuses to delayed (≥60 s) versus immediate (≤10 s) clamping of the umbilical cord. Systematic reviews with meta-analyses, including this and similar trials, show that delaying clamping in preterm infants reduces mortality and need for blood transfusions. Amongst 1,531 infants in APTS followed up at two years, aiming to delay clamping for 60 s or more reduced the relative risk of the primary composite outcome of death or disability by 17% (p = 0.01). However, this result is fragile because nominal statistical significance (p < 0.05) would be abolished by only 2 patients switching from a non- event to an event, and the primary composite outcome was missing in 112 patients (7%). To achieve more robust evidence, any future trials should emulate the large, simple trials co-ordinated from Oxford which reliably identified moderate, incremental improvements in mortality in tens of thousands of participants, with <1% missing data. Those who fund, regulate, and con- duct trials that aim to change practice should repay the trust of those who consent to participate by doing everything possible to minimise missing data for key outcomes.William Odita Tarnow-Mordi, Kristy Robledo, Ian Marschner, Lene Seidler, and John Simes, On behalf of the Australian Placental Transfusion Study, APTS, Childhood Follow Up Study Collaborator