A failed IVF transfer is particularly disappointing when the embryo has been tested by PGT-A and found to be chromosomally normal (euploid). After repeated failures, patients often wonder whether there is an underlying implantation problem and whether additional investigations or treatments are needed. A large 2026 study in Fertility and Sterility* provides reassuring—but also thought-provoking—evidence.

Most embryos that develop into blastocysts do so 5 days after fertilisation. Traditionally, this is the stage that has been considered the most likely to result in a successful pregnancy. However, some embryos take a day longer to reach the same stage, but may still be suitable for transfer. A new study* aimed to investigate

Implantation is the process by which a transferred embryo attaches to and embeds in the uterine lining (endometrium). For a day 5 embryo, this usually occurs within the first 24 hours following transfer, while for a day 3 embryo it typically happens within 2–4 days. Without successful implantation, pregnancy cannot develop. If implantation fails on