Huang J, Rong L, Zeng L, Hu L, Shi J, Cai L, Yao B, Wang X-X, Xu Y, Yao Y, et al. Embryo selection through non-invasive preimplantation genetic testing with cell-free DNA in spent culture media: a protocol for a multicentre, double-blind, randomised controlled trial. BMJ Open. 2022;12(7):e057254.