Each centre varies for their hormone assisted cycle. Our centre does 2 wweks of sniffing follwoed by 2 weeks of Progynova tablets to thicken the womb lining up. Once thick enough (8mm+) the the embryos are thawed and replaced. This cycle is ideal if natural has not worked or if they want to be absolutley sure the right hormones are in the right places to help implantation.
Sarah