Editing Embryo transfer (section)

== Uterine preparation ==
In the human, the uterine lining ([[endometrium]]) needs to be appropriately prepared so that the embryo can implant. In a natural cycle the embryo transfer takes place in the [[luteal phase]] at a time where the lining is appropriately undeveloped in relation to the status of the present Luteinizing Hormone. In a stimulated or cycle where a "frozen" embryo is transferred, the recipient woman could be given first estrogen preparations (about 2 weeks), then a combination of [[estrogen]] and [[progesterone]] so that the lining becomes receptive for the embryo. The time of receptivity is the [[Implantation (human embryo)|implantation window]]. A [[scientific review]] in 2013 came to the conclusion that it is not possible to identify one method of endometrium preparation in frozen embryo transfer as being more effective than another.<ref>{{cite journal | vauthors = Groenewoud ER, Cantineau AE, Kollen BJ, Macklon NS, Cohlen BJ | title = What is the optimal means of preparing the endometrium in frozen-thawed embryo transfer cycles? A systematic review and meta-analysis | journal = Human Reproduction Update | volume = 19 | issue = 5 | pages = 458–70 | year = 2013 | pmid = 23820515 | doi = 10.1093/humupd/dmt030 }}</ref>

Limited evidence also supports removal of [[cervical mucus]] before transfer.<ref name=mains>{{cite journal | vauthors = Mains L, Van Voorhis BJ | title = Optimizing the technique of embryo transfer | journal = Fertility and Sterility | volume = 94 | issue = 3 | pages = 785–90 | date = August 2010 | pmid = 20409543 | doi = 10.1016/j.fertnstert.2010.03.030 }}</ref>