By Neus Ferrando Gilabert BSc, MSc (embryologist).
Last Update: 04/02/2014

In vitro fertilization or IVF is an assisted reproductive technology.

The conventional IVF process is described step-by-step hereafter:

1. Controlled Ovarian Stimulation (COS). Specific hormones are administered to women for two main purposes: monitoring the exact moment of the ovarian cycle and producing a larger number of eggs so that several can be retrieved and fertilised. This may increase the technique’s success rate.

2. Follicular puncture (egg retrieval). If several ripe follicles are found, they will be retrieved by means of follicular puncture.

3. Semen collection and sperm preparation. The semen sample undergoes every analysis and testing necessary to guarantee its maximum quality. The man’s sperm is prepared so that the healthiest spermatozoa can be sorted out by means of capacitation.

4. Oocyte insemination. Mature eggs and capacitated spermatozoa are brought in contact with each other in a laboratory dish, enabling thus fertilisation to occur.

5. Embryo culture. The fertilised egg then turns into an embryo. Embryos are monitored and checked in order to see how, division after division, their number of cells increases. Embryo development is evaluated so that their quality can be determined and finally decide which ones can be considered as healthy embryos.

6. Embryo transfer. The healthiest-looking embryo is selected to allow the woman becoming pregnant successfully. Then, this embryo is transferred into the woman’s womb by means of a catheter. This process may take several minutes.

Furthermore, the remaining healthy-looking embryos are frozen. Poor-quality embryos are left in culture in the incubator while their progress is checked, although they usually do not survive this process.

7. Embryo freezing (a.k.a. embryo cryopreservation). This step is taken in order to allow the preservation of the embryos in perfect conditions. This enables them to be used on future occasions if necessary.

8. After embryo transfer: advice on two-week wait. It is advisable to follow a series of tips during the two-week wait (TWW or 2WW) before performing a pregnancy test. For instance, you should drink fluids and not engage in sexual intercourse.

Authors and contributors

 Neus Ferrando Gilabert
BSc, MSc
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information