Which is more important, the quality or the quantity of the eggs?

By Reproclinic Editorial Committee

One of the steps in an In Vitro Fertilization (IVF) treatment is what we call "ovarian stimulation". This step consists of administering hormonal injections to the patient with the aim of obtaining a greater number of eggs to fertilize in the laboratory. In the majority of cases, more than one embryo is obtained for transfer and  the rest of embryos with good quality that are not transferred are frozen for transfer in a later cycle (in the event of not becoming pregnant in the first cycle or, in the event of a pregnancy, in order to have the option of a second child).

What is more important, the quantity or quality of the eggs obtained? 

In this sense, one question that we sometimes heared from our patients during the process is how many eggs are necessary to succeed in the IVF treatment.  This is a complex question to answer, since, apart from the quantity, which is a very important factor and which always gives us more options for transfer, what interests us most when selecting the best eggs is their quality.

The quality of the eggs is equivalent to their capacity to be fertilised and to give rise to embryos which are competent to implant when the transfer is made to the patient's uterus.

It is true that the more eggs we obtain, the greater the probability that at least one of them will be of good quality and will give a gestation.  However, if its quality is not sufficient, it will be difficult to achieve a pregnancy.

Does a woman's age influence the quality of the eggs?

One of the most important factors in relation to the quality of the eggs is the woman's age.

It is very important for women to know and be aware that the number of eggs they have will diminish over time as they get older, so they will be lost throughout their reproductive lives until they reach menopause.  But in addition to a decrease in quantity, this will be accompanied by a decrease in the quality of the eggs.

When the woman reaches 35 years of age, this loss of quality becomes noticeable, being especially pronounced from the age of 40, when the probability of genetic alterations in the embryos is greater.

Fertility preservation

Faced with the decline in the quantity and quality of the eggs, there is little we can do. Although it is very likely that a woman at 35, 37 or 40 years old is at the peak of her life, the truth is that her biological clock is not playing in her favour in this respect.

Luckily, thanks to the vitrification of their eggs, a simple technique which freezes them in an ultra-fast manner, they can preserve their fertility until they decide the best time to become a mother, without their eggs losing quality and continuing to maintain the same age as when they were vitrified.