Correction to: Study protocol: baby-OSCAR Trial: Outcome after Selective early treatment for Closure of patent ductus ARteriosus in preterm babies, a multicentre, masked, randomised placebo-controlled parallel group trial - Samir Gupta; Edmund Juszczak; Pollyanna Hardy; Nimish Subhedar; Jonathan Wyllie; Wilf Kelsall; Sunil Sinha; Sam Johnson; Tracy Roberts; Elisabeth Hutchison; Justine Pepperell; Louise Linsell; et al. (BMC, 2021)