What external and internal factors may influence oocytes quality?
Is everything known for the doctors or are there any undiscovered facts about oocytes. What factors have bigger impact on oocytes and may decide about IVF outcome in overall. In 3on1 #IVFANSWERS our experts tell more in details abouts oocytes:
- Dr Alejandro Aldape Arellan – senior consultant in reproductive medicine, currently Medical Director of Institut Marquès Ireland
- Dr Inna Moroz – Fertility Specialist at ISIDA Clinic
- Dr Oksana Onyshchuk – Gynecologist-endocrinologist, fertility specialist, The Institute for Reproductive Medicine Prof. F. Dakhno Clinic
Answer from Dr Aldape Arellan - Medical Director
Although a great achievement has been made in oocyte quality, we doctors still don’t know everything about that. We can only separate the factors that may influence the oocyte quality as internal ones and external ones.
The internal factors would be all of those we do not have control of. For example, it can be age, genetics or chronic illnesses such as endometriosis or PCOS. The age probably is one of the most important factors. The younger we are, the better quality we are going to have. This goes of course also for women: the younger they are, the better quality the eggs are. The miscarriage rate will demonstrate clearly what I’m talking about. For a patient under 30 years old, the chances of miscarriage are from 10 to 15%. On the other hand, when we have a patient that is over 40 years old, the chances of having a miscarriage will be about 25-33%.
I also spoke about genetics. As you know, we have no control over genetics and it is really strongly influencing both the fertility and menopausal period for a patient. Although we cannot do anything about this, at least we have a back-up plan and we can advise our patients on this subject.
And then we have endometriosis and PCOS. Endometriosis is increasing oxidative stress so of course it is affecting the microenvironment of the ovary and therefore is affecting the egg quality.
Endometriosis also has a negative impact in terms of ovarian reserve.
When it comes to PCOS, we know that it is causing the imbalance between the hormones. For that reason it is changing the microenvironment of the ovary and harming the quality of the eggs.
The external factors influencing the oocyte quality are lifestyle factors, environmental factors and occupational factors. Here the most important would be lifestyle factors. I’m talking especially about smoking, alcohol, overweight. These are the ones we can change and modify. However, this doesn’t mean that when we change the lifestyle factors, we are always going to improve the quality of the egg. When we’re modifying our lifestyle, we’re doing this mostly in order not to harm the egg and not to improve its quality. Here we should also mention the caffeine and the controversy around it. Some people think it is not affecting anything, while the others think it’s affecting lots of things. In my opinion, if your regular intake is not more than 4 cups a day, it is still fine. However, over 4 cups a day may negatively impact the quality of the egg.
So in overall, I think that age is a factor that can mostly influence the quality of the egg.
Answer from Dr Moroz - Fertility Specialist
The quality of oocytes can be influenced by multiple factors. It is relating not just to an external feature that your embryologist can see under a microscope but it also about the ability of the egg to form a healthy embryo.
Some conditions like endometriosis or PCOS can also affect the ability of oocytes to create a healthy embryo. However, the main factor is the age of a woman. The older a woman, the worst the situation she’s in. The quantity and quality of eggs will decrease with years – the crucial time is up to 35 years old. So if you’re not planing your pregnancy not right now but later in life, consider freezing of your eggs. It will be much simpler for you in the future.
Other factors that can influence the quality of oocytes are genetic predisposition to early menopause or premature depletion of your ovarian reserve as well as unhealthy lifestyles ( e.g. overweight). All those things create hormonal imbalance in your body and this may result in specific changes in the quality and quantity of your eggs. Stress, medications or surgeries can also have some influence. So be sure to ask your doctor about all these important things and how to improve it.
Answer from Dr Onyshchuk - Gynecologist-endocrinologist, fertility specialist
I think that the first and most important factor is age. These days, career and education are more important for women than marriage and childbearing. The older a woman is, the fewer chances for live births she has.
Other factors which may reduce the ovarian reserve quantity and quality of eggs are: surgery treatment in the ovaries, chemotherapy at a young or reproductive age, hormonal disorders (high or low levels of TSH), PCOS and endometriosis in women of reproductive age. These factors alone or in a combination may cause primary ovarian insufficiency.