The process by which patients in a clinical trial are randomly assigned to different treatments. Randomisation minimises the differences among groups by equally distributing people with particular characteristics among all the trial arms. It is considered the best way to assess the efficacy of a given medical treatment.

Randomised controlled trial (RCT)

In a RCT, the research participants are randomly allocated, usually by computer, to either the control or the active arm of the study. Those in the active arm are given the new treatment, while those in the control group are given either an inert placebo or the current best available treatment. Researchers will be interested in whether more of the patients in the active arm are showing signs of improvement than in the control group. RCTs are considered to be the ‘gold standard’ in medical research.


Royal College of Obstetricians and Gynaecologists. The RCOG is dedicated to the encouragement of the study and the advancement of the science and practice of obstetrics and gynaecology.
Royal College of Obstetricians and Gynaecologists website 


Royal College of Paediatrics and Child Health. The main objectives of the College are to advance the art and science of paediatrics, improve standards of medical care to children, and to educate and examine doctors in paediatrics. Additionally, the College has a function in providing information to the public on the healthcare of children.
Royal College of Paediatrics and Child Health website

Reproductive tourism

Term that refers to people going abroad for fertility treatment rather than accepting the treatment choices available in the UK.


Retinopathy of Prematurity. A serious eye problem that can affect premature babies.