People with a high Body Mass Index can make good stem-cell donors. In the past obese people got side-effects after donating. people with a BMI of up to 40 may donate. Stem cell transplants are used in the treatment of blood cancers. Dr Rachel Pawson check 19 people with a BMI of over 35 for a year after they donated. The study found that the donors no side effects than people donating. Previously, both registries had not accepted donors with a BMI of 35 or above. Dr Annelies Billen see evidence that the method was safe for donors with higher BMIs. Registries in USA, Canada and Germany have relaxed their policies to allow donors with BMIs of up to 40 in recent years.