By Laura Garrido BSc, MSc (embryologist).
Last Update: 04/22/2014

The moment in which a woman is about to undergo an assisted reproductive treatment such as in vitro fertilisation, she is required to endure a controlled ovarian hyperstimulation, that is to say, providing hormones in order to obtain a larger number of eggs within the ovary.

Naturally, women produce an egg monthly. However, an egg is not enough to perform an IVF, since chances for pregnancy would be almost non-existent.

Oocytes for IVF

Ovarian stimulation is performed due to this reason. By means of different medicaments, the development of more than one follicle within the ovary is controlled. The whole process in controlled with a transvaginal ultrasound in order to check that the follicles are developing well.

Number of eggs after ovarian stimulation

Once the gynaecologist observes that the eggs are fully developed, the follicular puncture through which the eggs will be extracted is scheduled.

The hormone treatment is highly personalised, since each patient’s response to hormones is different. If the woman does not have any hormonal imbalance, a minimum of 8 eggs and a no more than 18 eggs should be collected.

More than 20 eggs does not mean greater chances for getting pregnant but quite the opposite. If too many eggs are produced at the same time, they may present a poor-quality. Poor-quality eggs are hard to be fertilised correctly and, thus, giving rise to an embryo is less probably. In addition, embryos grown out of these kind of cycles present lower survival rates.

Number of eggs after ovarian stimulation

Thus, the most important thing is not the quantity, but the quality of the eggs obtained. With more than 20 eggs, their quality decreases, which translates in fewer chances for pregnancy.

Authors and contributors

 Laura Garrido
BSc, MSc
Embryologist
Bachelor's Degree in Biotechnology from the Pablo de Olavide University (UPO) of Seville, Spain. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI). Experience at IVF, andrology, and general analysis laboratories. Embryologist specialized in Assisted Reproduction. More information