Hreinsson 2004.

Study characteristics
Methods	Study type: randomised controlled trial in parallel groups Country: Sweden
Participants	Number of participants randomised: 144 Age: BS 32.1 and CS 33.1 Number of previous treatments: not stated Infertility duration: not stated Prognosis: good; excluded poor responders Inclusion criteria: women undergoing IVF or ICSI treatment cycles, who had at least six follicles as observed at the final ultrasound scan before hCG administration were allocated to the study, after they had given informed consent. Exclusion criteria: not described
Interventions	BS group: N = 64 CS group (day 3): N = 80 Description of the cycles: Long protocol (down‐regulation with GnRH agonist and stimulation with rFSH) or short protocol with Cetrorelix Injected oocytes were collected into IVF‐medium (Vitrolife, Gothenburg, Sweden). The embryos were cultured from day 1 to day 3 in IVF‐medium and from D3 to D5‐6 in CCM‐medium'(Vitrolife). In the first 50 cases, sequential media was used( G1/G2 Vitrolife).
Outcomes	Clinical pregnancy rate
Notes	Prognosis: good; excluded poor responders Mixture of media types and ET policy change over course of study Outcome no advantage of blast culture Letter sent and reply received