Compare, in young patients with In vitro fertilization (IVF), the rate of embryo implantation by early culture transfer (J2-J3) between 2 groups of patients: "normo responders" vs. "poor responders".

Inclusion Criteria:

• IVF patient managed with or without ICSI between 01/01/2014 and 30/06/2015 in one of the two study centres
• Age < 35 years old
• Fresh transfer of at least one embryo between D2 and D6
• patients who have already received one or more transfer attempts.

Exclusion Criteria:

• No fresh transfer (Freeze All, segmentation failure, stimulation failure)
• Double successive embryo transfer (e. g. J3-J5). We did not retain these cases because if only one of the 2 embryos is implanted, it is not possible to know which transfer it corresponds to.
• Maternal serum FSH determination < 4 IU/ml at D3 in the baseline balance sheet (hypogonadotropic hypogonadism)

The population concerned is all young patients, defined as being under 35 years old, who have benefited from IVF in the 2 inclusion centres (Centres d'Aide Médicale à la Procréation des CHU de Nîmes and the Saint Roch clinic in Montpellier) between 01/01/2014 and 30/06/2015.