ISRCTN94726536.

Methods	Prospectively randomised controlled study
Participants	500 women undergoing ICSI and embryo culture Inclusion criteria: Female patients with at least 1 previous unsuccessful in vitro fertilisation (IVF) attempt, in which a clinical pregnancy was not established (including biochemical pregnancies or miscarriages) Aged between 25 and 45 Exclusion criteria: Women older than 45 years Patients with male partners with testicular spermatozoa or severe oligoasthenoteratozoospermia (total sperm number less than 1,000,000 and sperm motility less than 5%)
Interventions	Participants are randomly allocated to 1 of 2 groups. Group 1: Participants receive ICSI treatments carried out using ISM1 for embryo culture and transfer. Group 2: Participants receive ICSI treatments carried out using EmbryoGen for embryo culture and transfer.
Outcomes	Primary outcome measure: Implantation rate (defined as the number of implanted embryos per number of transferred embryos) is measured 30 days after embryo transfer. Secondary outcome measure: Pregnancy rate (defined as the number of pregnancies per number of transferred embryos) is measured using ultrasound of gestational chamber 30 days after embryo transfer.
Notes	Country of recruitment: Italy Overall trial status 'completed' Publication status 'results overdue' Unable to determine if women or embryos were randomised Emailed contact author 29 October 2019, but received no response