A blastocyst is an embryo that has grown in the laboratory for 5–6 days and is ready for transfer to the uterus. Compared to embryos transferred earlier (after 2–3 days), blastocysts are more developed, stronger, and have a higher chance of successful implantation.
Not all embryos reach this stage, but those that do are usually healthier and give a better chance of pregnancy. Blastocyst culture also helps doctors select the best-quality embryos, which increases success rates and lowers the risk of multiple pregnancies.
This method is often recommended when earlier fertility treatments have not worked.
