Editing In vitro fertilisation (section)

===Embryo culture===
{{Main|Embryo culture}}
The main durations of embryo culture are until [[human embryogenesis|cleavage stage]] (day two to four after [[co-incubation]]) or the [[blastocyst]] stage (day five or six after [[co-incubation]]).<ref name="DarLazer2014">{{cite journal | vauthors = Dar S, Lazer T, Shah PS, Librach CL | title = Neonatal outcomes among singleton births after blastocyst versus cleavage stage embryo transfer: a systematic review and meta-analysis | journal = Human Reproduction Update | volume = 20 | issue = 3 | pages = 439–448 | year = 2014 | pmid = 24480786 | doi = 10.1093/humupd/dmu001 | doi-access = free }}</ref> Embryo culture until the blastocyst stage confers a significant increase in [[live birth rate]] per [[embryo transfer]], but also confers a decreased number of embryos available for transfer and [[embryo cryopreservation]], so the cumulative clinical pregnancy rates are increased with cleavage stage transfer.<ref name=":0" /> Transfer day two instead of day three after fertilisation has no differences in [[live birth rate]].<ref name=":0" /> There are significantly higher odds of [[preterm birth]] ([[odds ratio]] 1.3) and [[congenital anomalies]] ([[odds ratio]] 1.3) among births having from embryos cultured until the blastocyst stage compared with cleavage stage.<ref name="DarLazer2014"/>