Everything you need to know about oocyte and egg quality

First of all, what is an oocyte? An oocyte is a developing or immature egg (ovum). Women are born with all the oocytes that they will have, and normally in each cycle, only one of them will become a mature egg (1). This mature egg is the one released from the ovary, where it can be fertilized (2).

It is well known that female fertility begins to decline at the age of 32 and this is even more pronounced after the age of 37. Several factors influence the reduction of successful pregnancies related to age, but it seems like oocyte quality is the major contributing factor (3). Added to this, the number of oocytes naturally decreases with age (1), which also favors fertility issues.

What affects the oocytes health?

Oxidative stress is one of the most relevant factors that influence the aging of cells, and specifically in the ovaries, to the reduction in the number and quality of oocytes. For this reason, antioxidants like N-acetyl-L-cysteine (NAC), melatonin, and vitamin E have an important role in keeping ovarian function and fertility (4). In hand with this, avoiding habits that promote oxidative stress, such as smoking, not exercising, stress and an unhealthy diet, also beneficiate ovarian health.

Other factors, such as the exposure to pesticides from fruits and vegetables, contaminated water, gardening supplies, and some cosmetic and cleaning products, can also generate fertility problems. These substances can affect female sex hormones, disruption of the menstrual cycle, and oocyte alterations (4).

An interesting finding has been that in experiments with mice, a caloric restriction improved the oocyte quality. Maintaining a healthy weight seems to contribute to the preservation of fertility. The mechanism of such a thing is not completely elucidated, but one of the reasons could be the generalized inflammation that occurs in obesity, related to greater oxidative stress and cell damage (4).

The quality of the oocyte influences the early survival of the embryo, the establishment and maintenance of pregnancy, the development of the fetus, and even adult disease (5). For this reason, it is important to create an environment and lifestyle that favors as much as possible a good oocyte quality if you’re trying to conceive.

References 1.https://www.verywellfamily.com/oocyte-definition-and-development-1960091#:~:text=An%20oocyte%20is%20an%20immature,several%20follicles%20begin%20to%20develop. 2.https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/expert-answers/ovulation-signs/faq-20058000#:~:text=Ovulation%20is%20the%20process%20in,where%20it%20can%20be%20fertilized. 3.Ben-Meir, A., Burstein, E., Borrego-Alvarez, A., Chong, J., Wong, E., Yavorska, T., Naranian, T., Chi, M., Wang, Y., Bentov, Y., Alexis, J., Meriano, J., Sung, H. K., Gasser, D. L., Moley, K. H., Hekimi, S., Casper, R. F., & Jurisicova, A. (2015). Coenzyme Q10 restores oocyte mitochondrial function and fertility during reproductive aging. Aging cell, 14(5), 887–895. https://doi.org/10.1111/acel.12368 4.Ahmed TA, Ahmed SM, El-Gammal Z, Shouman S, Ahmed A, Mansour R, El-Badri N. Oocyte Aging: The Role of Cellular and Environmental Factors and Impact on Female Fertility. Adv Exp Med Biol. 2020;1247:109-123. doi: 10.1007/5584_2019_456. PMID: 31802446. 5.Krisher RL. The effect of oocyte quality on development. J Anim Sci. 2004;82 E-Suppl:E14-23. doi: 10.2527/2004.8213_supplE14x. PMID: 15471793.