There is substantial evidencethat blastocyst transfers are better than cleavage stage transfers. Thisprompts companies to produce media to support embryo development to theblastocyst stage. Studies have shown that its considered appropriate to placeembryos in a media up to day 5. Collaterally, a buildup of waste products arises,so its recommended to renew the media on day 3 to minimize waste concentration (Leese and Brison, 2015). Growth of ART embryosremain inferior to in vivo embryonic procedures, indicating that in vitro procedures invokecellular and metabolic stress on the embryo, forcing it to spend energy toadapt to the foreign environment. Stress due to culture leads to an increase ofglucose uptake, respiration and lactate production within 1 – 6 hours ofpost-compaction (Leese and Brison, 2015).
Thus, the manipulations of embryosduring IVF induces stress responses and epigenetic changes linked to thoseresponses (Leese and Brison, 2015).