What does a good number of eggs recovered for IVF mean?

⥂ What to expect?

In almost all IVF cases, the initial stage involves the ovarian stimulation phase and the subsequent induction of ovulation. The ultimate goal of this stage is to cause multiple eggs to mature in one cycle, instead of just one egg, as is normally the case. It allows us to retrieve a greater number of eggs, thus increasing the success rates of IVF. Many women against the IVF procedure who are about to start the stimulation phase wonder what is the average number of eggs that is considered good for the success of the procedure. In fact, there is no single answer to this question, as we will explain in the following sections.

Ovarian response during IVF cycles

The ovarian stimulation procedure used in all IVF/ICSI cycles involves the administration of exogenous hormones. The stimulation phase lasts approximately 10-12 days. The ovarian response during IVF cycles varies from woman to woman depending on each patient’s characteristics, medication protocol, cause of infertility, etc. With this in mind, we can distinguish three types of responders to IVF drugs:

Poor responders

When the number of eggs recovered is 3 or less. It usually corresponds to women with poor ovarian reserve due to age, as well as women with certain conditions that prevent the development of a higher quantity of eggs.

Normal responders

Fortunately, most women can be included in this second group. This means that a good number of eggs are recovered after stimulation. In general, the average number of eggs is 10 per cycle.

High responders

We include here cases where 15-20 or more eggs are obtained per cycle. The profile of these patients is usually associated with young girls, without fertility problems.

During the stimulation phase, I will need to see you 2 to 3 times to monitor your response to the IVF drugs. Depending on the results, we may need to adjust the dose you are given. It should be noted that being included in any of the groups described above does not translate into an underlying problem. In other words, a 45 year old woman is expected to be a poor responder.

What is a good number of eggs to be recovered (collected)?

Egg retrieval, medically known as egg retrieval, is a surgical procedure in which eggs are collected from the ovary. The purpose of this surgery is to harvest the eggs when they are in metaphase II, which is considered the optimal state of maturation for retrieval and fertilization. In order to schedule the egg retrieval at the right time, i.e., before spontaneous ovulation, and to be able to predict the number of eggs that can be retrieved, two aspects are evaluated: follicle size and estradiol levels. Each follicle contains an egg inside, which produces oestradiol. However, many times the follicle is empty at the time of egg retrieval or contains an egg but is immature. In other words, fertilisation is not possible in these cases. In short, the number of eggs retrieved after ovulation may be lower than the number of follicles observed on ultrasound or estimated according to the amount of estradiol in the blood.

According to the size of the follicles

The size of the follicles is measured with the help of gynaecological ultrasound. As the egg matures, the follicles increase in size. When a follicle reaches a size of 16-18 mm, it is considered mature enough to contain a mature egg inside. At this point, we will schedule the ovulation within 36 hours. This allows us to estimate the number of mature oocytes that will be ready to be retrieved during the collection process.

According to estradiol levels

Approximately, each mature follicle equals 200-300 pg/ml of estradiol. With this in mind, it is possible to estimate the number of mature oocytes that will be recovered based on estradiol levels.

Oocyte quality versus quantity

The ultimate goal of any IVF procedure is to achieve pregnancy. But first, viable embryos must be created. And by viable embryos, we mean embryos that can attach to the uterus (endometrium) to result in pregnancy. So, regarding the title of this post, what is a good number of eggs recovered during IVF?

The answer is simple: quantity is not as important as quality.

However, it is true that the higher the number of eggs recovered, the greater the chances of creating more embryos. However, if the quality of the eggs retrieved is not good, we will not get pregnant even if a large number of eggs are retrieved. As can be seen in the table below, age also plays an important role in determining the number of eggs recovered. On the other hand, it should be borne in mind that the number of eggs does not always match the number of embryos. Not all of the eggs collected will be fertilised. In conclusion, obtaining a large number of high-quality eggs is essential, as it is likely to translate into a large number of viable embryos. In these cases, a proportion of these embryos can be cryopreserved (frozen) for transfer to subsequent cycles, in case the first attempt is not successful or because you want to have more children.