Ovarian reserve

Ovarian reserve is a term that is used to determine the capacity of the ovary to provide egg cells that are capable of fertilization resulting in a healthy and successful pregnancy. With advanced maternal age the number of egg cell that can be successfully recruited for a possible pregnancy declines, constituting a major factor in the inverse correlation between age and female fertility. While there is no known method for assessing the ovarian reserve of individual women, indirect determination of ovarian reserve is important in the treatment of infertility. The ovary is generally thought of as an egg bank from which the woman draws during her reproductive life. The human ovary contains a population of primordial follicles. At 18–22 weeks post-conception, the female ovary contains its peak number of follicles (about 300,000 in the average case, but individual peak populations range from 35,000 to 2.5 million). The size of the initial ovarian reserve is strongly influenced by genetics. Also, elevated androgen levels during prenatal development have an adverse effect on the early establishment of the ovarian reserve. The ovarian reserve is at maximum value in sixth month old embryos. Then this amount is only decreasing, as there is no new synthesis and differentiation. There is a huge decrease before the child is born, being this pool reduced from over 8 million potential oocytes to 2 million. The amount continues decreasing progressively until reaching the age of 30 years old, in which there is a dramatic decrease. There are about 1 to 2 million oocytes when a woman is born. From them, 400000 oocytes will reach the stage of puberty and only 400 will rise maturation and ovulation. The rest of them reach atresia, a natural apoptotic process leading to the breakdown of the follicle. Each menstrual cycle one egg cell is released by ovulation. In addition, the remaining follicles that were recruited towards maturation are lost by atresia. Few if any egg cells are replenished during the reproductive years.