Pregnancy after treatment
The implantation window is the limited time — commonly a few days in the mid-luteal phase — during which the endometrium can accept an embryo. Treatment cycles aim to synchronise the embryo's stage with this window, which is why the number of days of progesterone before a frozen transfer is specified so precisely.
Also known as: window of implantation, WOI
Related South Africa guides
Sources
- ESHRE/ICMART glossary and ESHRE laboratory guidance
Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.