The aim of the research is to evaluate the results of the first in vitro fertilization (IVF) attempt according to the type of embryo culture. From the fertilization to the day 2 transfer, embryos are cultured in standard incubator or in a time lapse technology (TLT). TLT offers an uninterrupted culture environment with a morphokinetic evaluation, whereas culture in standard incubator involves discontinuous morphological embryo evaluation. The principal objective is to compare the live birth rate after the fresh embryo transfer, in a cohort of women less than 39 years-old.

Embryo evaluation and selection is fundamental in clinical IVF in order to obtain a live birth in a shorter delay as possible, but minimizing the risk of multiple pregnancies. TLT was introduced few years ago in clinical practice and allows the continuous follow up of the embryo development. In IVF centers, embryos are preferentially cultured in TL system with undisturbed environmental conditions. This provides information about the development of the embryos in time intervals of 15min and adds kinetic criteria for embryo evaluation and selection. In conventional incubator, the follow up of embryo development consists in 3 static time point observations. Many reviews and observational studies have discussed the value of time-lapse monitoring but it is as yet unclear, however, whether the TLT improves the results of IVF. It has been suggested that the clinical benefits of applying new technologies should be verified and documented by randomized controlled trials. Moreover, the cumulative live birth rate and the delay for conception were rarely reported. The study aims to evaluate the results of the first IVF attempts comparing classical embryo culture in standard incubator and embryo culture and follow up in TLT. The hypothesis is that the undisturbed culture and the selection based on continuous time-lapse images improve the results of the single embryo fresh transfer and increase the cumulative live birth rate. Patients will be randomized the day of the puncture for the type of culture: standard incubation or TLT. The results of the fresh and successive vitrified-warmed embryo transfer will be prospectively collect and patients will be followed until live birth. The attempt will be considered ended after a live birth, if all the frozen embryos are transferred, after 24 months follow up or after surrender.

Inclusion Criteria:

• first IVF/ICSI attempt with fresh transfer,
• women ≥18 years-old and <39 years-old,
• signed informed consent

Exclusion Criteria:

• attempts with donor,
• comprehension problem,
• frozen gametes,
• BMI>35 kg/m2,
• history of 3 or more miscarriages,
• uterine pathology,
• serodiscordant patients