Table 2. RCTs - Table with additional information and comments. In the top the women were randomized, in the lower two studies the oocytes were randomized.
Reference	Country/year Multicenter/single-center	Randomization of women/oocytes	Number of participants	Comments
Kleijkers et al. 2016	The Netherlands, 2016 Multicenter	Women were randomized by a computer program	836 women, birthweight data from 360 children	Detailed description of methods used. Many participants. Blinding of couples, gynecologists, fertility doctors, outcome examiners. Intention to treat. Good description of handling dropouts. Power calculation included.
Ceschin et al. 2016	Brazil, 2016 Single-center	Women were randomly divided into two groups (not described in detail)	60 women, 311 mature oocytes for ICSI	Few participants. Acceptable description of methods, but short and not very detailed.
Hassani et al. 2013	Iran, 2013 Single-center?	Women were randomized before oocyte pick up according to a randomization list based on sequential numbers in sealed envelopes	538 women	Many participants. Good description of methods. Clear inclusion criteria of the women.
Zhang et al.,2016	China, 2016 Single-center	Oocytes were randomized according to a randomization table	37 women, 620 oocytes, 64 embryos transferred	Few participants. Good description of methods used. Focus is on early embryo cleavage kinetics.
Hambiliki et al.,2011	Sweden, 2011	Oocytes were divided to type of culture media via alternate allocation	110 women, 1206 oocytes, 108 embryo transfers	Many participants. Good descriptions of the methods with clear inclusion criteria and definitions of the outcomes.