March 6, 2023 Author : Miguel Tuna Until a few years ago, female fertility preservation techniques were used only for women who suffered some disease associated with infertility or who underwent treatments that could compromise their fertility, like those causing a marked decrease in ovarian reserve or even a premature menopause. With late-age maternity that has characterized the last few decades and with the evolution and consequent greater use of fertility preservation techniques, these have also become more used in other circumstances: Safeguard the existence of own and younger reproductive cells, with a view to have a biological pregnancy . How does female fertility evolves Throughout reproductive life, from puberty to menopause, woman fertility decreases, which is related to the quantity and quality of oocytes . At birth, the number of ovarian follicles in each woman is determined: primordial ovarian follicles are formed in the ovaries of female fetuses during pregnancy and reach their maximum number in the middle of pregnancy; Although the follicles remain in a resting state until the onset of puberty, at this point their number is already around 30% of those present at birth; In each menstrual cycle, several follicles are lost (about 1000!), because although in most cases only one ovulate, others start their development and are lost afterwards; On average, by the age 30, about 95% of women have 12% of the ovarian follicles they were born with; At age 40, ovarian follicles are only 3%; At menopause, primary follicles are depleted; In addition to quantity, the quality of ovarian follicles also decreases during reproductive age. The greatest difficulty that most women have in getting pregnant after the age of 35-40 is related to the number and quality of their oocytes. How is fertility preserved? Preserving female fertility means harvesting and preserving viable sexual cells (oocytes or ovarian tissue) by vitrification , to be used later for the purpose of a biological pregnancy. Oocytes or ovarian follicles are collected from the ovaries by puncture performed through the vagina, under sedation; These oocytes are collected at the stage of development they reach before ovulation occurs; Before collecting the oocytes, a hormonal stimulation treatment for the development of the follicles is carried out, so that it is possible to collect them in greater numbers and thus increase the probability of having viable oocytes at the time of their use; After being collected, the oocytes are treated and preserved by vitrification, which is a form of cryopreservation, at a temperature close to -200 o C, in equipment and places suitable for this purpose. Ideally, the collection of oocytes for fertility preservation should be done between the ages of 30-35, but it can be done at any age . Read also : Oocyte cryopreservation step by step Use of cryopreserved oocytes The cryopreserved oocytes are used for medically assisted procreation (PMA) techniques . In vitro fertilization of thawed oocytes with sperm is performed, followed by implantation in the uterus of the embryos resulting from the fertilized ova. The majority - about 90% - of vitrified / cryopreserved oocytes remain viable when thawed, after periods of 5 to 10 years. There is currently no other upper legal limit for use of cryopreserved oocytes other than the woman's 50 years of age. Know that: The preservation of fertility by vitrification / cryopreservation of oocytes is a possibility that currently exists, which should be known by women who want to have children, but who do not know when they will have this desire and opportunity . It is not the solution for all infertility situations, it may be a solution to overcome fertility problems associated with a decrease in ovarian reserve. A pregnancy achieved from the woman's own cryopreserved oocytes allows: Avoid using donor eggs when it is not possible to get pregnant naturally; Having a biological child generated from younger cells (because they were collected at a younger age) that do not have the potential problems associated with older oocytes. In Hospital da Luz, specialists in Reproductive Medicine have experience in this area and can help clarify whether fertility preservation by cryopreservation of oocytes is a suitable option for each woman . The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
