Answer from: Saghar Kasiri, Clinical Embryologist
It’s estimated that we are born with around one to two million follicles that hold the premature eggs in them when we are born. Therefore by the age of puberty they are estimating that we have about three to four hundred thousand follicles remaining because unfortunately our ovaries are not very efficient and a lot of these follicles that can contain the immature eggs will be disintegrated and lost by the age of puberty around 300 to 400 thousand of egg reservoir in most women.
Every month that we get our menstrual cycle, we go through our menstrual cycle and get our period, we have about seven hundred to a thousand follicles start developing in the ovary but only one of them wins the race and becomes the mature egg that we produce every month so really again we’re not very efficient through our menstrual cycle. We lose with every ovulation around 700 to 1000 follicles so if you think that this reservoir keeps going down with every period that we have no wonder that by the age of 35 we have less number of eggs available in our ovaries and by the age of 40 plus this reservoir goes down quite low.
We do not produce new eggs like men produce new sperm continuously.
Answer from: Tomas Frgala, PhD
The age of the woman is very important. The quality of the eggs actually depends on the age of the woman and their quality is best between 20 and 30, then good until 35 and acceptable until 40. After 40 it gets really complicated and there’s hardly anything that you can do to improve that situation. So age is still crucial.
Answer from: Sokratis V. Grigoriadis, B.Sc, M.Sc
This is a central question in order to better understand biology aging for the oocyte. When considering oocyte quality we should always take into account that oocytes are sensitive cells, which are produced during fetal life and do not have the ability of self-renewal. This means that everything we do in our daily life could negatively impact oocyte quality and thus our reproductive potential. It is widely accepted that as maternal age increases oocyte quality is progressively compromised. This reduction regarding both oocyte quality and ovarian reserve starts approximately after 30 years of age, becomes more intense after 35 and peaks after 40. It is a natural process where the cellular and the molecular mechanisms regulating proper oocyte functionality are compromised in several levels. Thus, errors are observed mainly with regards to the mechanisms regulating chromosome segregation during the meiotic divisions. Meiosis is a special category of cell division, which takes place during gamete production in both females and males. Errors in meiosis affect the number of chromosomes for gametes and subsequently for embryos, finally leading to aneuploidy. Thus, women of advanced age have an increased risk of embryo aneuploidy such as trisomy 21, which is widely known as Down syndrome. Apart from errors during meiosis, oocyte aging can also cause telomere shortening. Telomeres constitute short DNA sequences found at the end chromosomes which protect the genetic information from damage. As maternal age increases telomere shortening is observed, making DNA more sensitive to damage. In the same context, during our lifespan several external and internal factors can cause damage to oocyte DNA, namely mutations. Oocytes are equipped with a perplexing network of molecular factors which can successfully locate and repair these damages. However, as maternal age increases, the efficiency of these repair mechanisms is significantly impaired resulting in mutation accumulation. These mutations negatively impact both oocyte quality and its competence. Oocyte competence refers to the ability of an oocyte to successfully support embryo development. Moreover, aged oocytes are characterized by impaired mitochondria functionality. Mitochondria are small subcellular compartments serving as the ‘’powerhouse’’ of a cell, producing chemical energy required for proper oocyte functionality. Moreover, mitochondria are able to protect oocytes from the damaging effects of reactive oxygen species, which are produced from several biological and environmental processes. Thus, aged oocytes are very sensitive to oxidative stress and cannot successfully support early embryo development. In summary, oocyte aging is a normal, albeit complex biological process which is associated with impaired embryo development, embryo aneuploidy and adverse obstetrical, perinatal and neonatal outcome. Despite the fact that we cannot avoid or reverse oocyte aging, we can adopt healthy lifestyle behaviors in order to improve aging-related deterioration of oocyte quality.
How does age affect egg quality?
Studies proved that the number of eggs decreases with age. Age is affecting not only the number of eggs but it has an effect on its quality. Over the age of 35 the chances for miscarriage caused to abnormal embryos dramatically rises. We need to keep in mind that pregnancy in advanced age is also at higher risk for both and child and mother.