A number of couples dealing with the issue of infertility sometimes fail to recognise one particular fact that may be the root cause behind their unsuccessful conception – the age factor.
Maternal age in particular, is an important consideration in order to determine the egg quantity and quality and, later, the embryo quality after fertilisation.
Women’s Age and Eggs
Fertility decreases with a woman’s age. This is because every woman has millions of eggs or, more specifically, follicles that mature into eggs inside her body when she is born.
By the time she reaches puberty, though, the number of these follicles drops down to about 300,000 to 400,000. During the monthly menstrual cycles, approximately 20 eggs start the journey to maturity but only one or two are finally able to complete this journey and are fit enough to be fertilised. These are the ‘good’ eggs.
Therefore, as you start aging, the number of eggs inside your body (egg quantity) and the number of good eggs that could have been fertilised (egg quality) keep depleting. Consequently, over time the chance of fertilisation also drops.
Egg quality and quantity are together known as the ovarian reserve and at any particular time, two women of the same age may have very different statistics in terms of this ovarian reserve.
But, in general, it has been found that the pregnancy rate begins to decline when people reach their the early 30s while the percentage of infertile couples starts increasing as follows:
- By age 30, 7%
- By age 35, 11%
- By age 40, 33%
- And at age 45, 87% of couples are infertile
An egg is said to be of good quality if it has good normal chromosomes and it can easily combine with sperm to develop into an embryo. In order to fertilise the egg, sperm need to be healthy enough to travel and reach the fallopian tube (and yes, the quality of sperm also goes down as a man ages, the change is just more subtle and gradual).
However, an egg needs to be both healthy enough to fertilise and have the essential qualities necessary to divide and grow into a healthy embryo.
Eggs with abnormal chromosomes or those that just have the cytoplasm (the jelly-like material that comprises the cell) cannot ensure successful pregnancy.
Also, after fertilisation occurs, eggs need to have ample energy to grow and mature, which is supplied by the mitochondria present in the egg cells. If this energy is not sufficient then the embryo will eventually disintegrate, leading to miscarriage.
There are good and bad eggs from the very start in any female’s body, but usually the number of eggs of superior quality are present at a higher volume at a younger age than after 30.
While analysing the egg quality, although age is an important factor, no two women can have the same number of good eggs. Egg quality is also affected by external sources like radiation therapy, smoking, chemotherapy and health conditions like endometriosis.
Egg Quality and Fertility
Poor egg quality may lead to infertility and repeated miscarriages due to one of these reasons:
- Egg does not implant into the uterine wall after fertilisation
- Egg implants but cannot grow due to insufficient energy
- With increased age of the mother, the age of the eggs also increases and leads to abnormal chromosomes. Children born may have genetic abnormalities, like Down’s syndrome.
Testing Egg Quality
Unfortunately, there is no accurate test for measuring egg quality. However, some tests, like the FSH test or the clomid challenge test, will give an estimate as to the number of good quality eggs present in your reproductive system.
Day 3 FSH Test
Follicle stimulating hormone, or FSH, is a hormone produced by the pituitary gland that triggers the development of several ovarian follicles inside the ovary.
When one of the follicles starts maturing into an egg, the hormone estrogen is released into the bloodstream. This acts as a signal for the pituitary gland to stop producing FSH. If the egg is not formed, then the amount of estrogen in the blood will be very low while the FSH level will continue to increase to about 40 mlu/ml of blood.
The FSH test is therefore used to analyse the amount of FSH in the blood using a blood sample, usually taken on the third day of your menstrual cycle (the third day of bleeding).
This gives a somewhat reliable result as to whether your ovaries have quality eggs for fertilisation or not. The higher the amount of FSH found in your system, the lower the quality of eggs.
Clomid Challenge Test
This test is also known as the clomiphene citrate challenge test or the CCCT. While the FSH test is performed on the third day of the menstrual cycle, this particular test is done on the tenth day.
For the test, you are given a dose of clomid anytime between the fifth and ninth day of your cycle. On the tenth day, the FSH level in your blood is analysed using a blood sample. Again, if the hormone level is high, it means the numbers of eggs inside the body have diminished.
Certain treatments, which are otherwise used to treat infertility, can also be helpful in analysing the quantity and quality of your eggs.
For example, poorer quality eggs will react differently to injections of gonadotropins while fertility specialist can examine the egg itself when it is removed from the body during in vitro fertilisation.
While in the past there were few options for women with declining egg quality, nowadays treatments like ivf, fertility drugs, and donor eggs have brought in much hope for women with poor egg quality.
Fertility drugs work by promoting ovulation by stimulating hormones that help mature an egg and release it from the ovaries each month.
Many fertility drugs, including Clomiphene, Human Menopausal Gonadotrophin, and Bromocriptine, have been safely and successfully used for many years to treat infertility.
Assisted Reproductive Techniques
Assisted procedures, such as IVF, remove eggs from the female body and fertilise it with sperm from the male body in lab conditions. Sometimes drugs may be administered to trigger superovulation inside the ovaries, which help to get more than one egg from the female body.
This allows specialists to choose those eggs with better cellular structure and function to be used for the in vitro fertilisation process.
Even methods like IUI combined with superovulation can be an option to overcome poor egg quality.
For all these procedures, it is important to note that age is still a decisive factor. Women above the age of 40 have about a 5% to 8% chance of conceiving after undergoing IUI as compared to the 15% to 20% chance for woman between the ages of 20 and 30. Ivf success rates, too, are a lower for older women.
Use of donor eggs can be a better option for women suffering from poor egg quality. The success rates for various fertility treatments tend to be higher when a donor egg is used, especially if the donor egg is from a woman in her 20s or 30s.
The process, however, involves overcoming many psychological, social, ethical and legal barriers. Those wishing to opt for donor eggs should first carefully analyse the pros and cons, and the complete procedure involved before moving forward.
Research is presently on to find ways to improve egg quality, like transferring the cytoplasm of a healthy donated egg into a poor quality egg or nuclear transfer.
Although these techniques are still too new to be used among the general public, they do fill the future with much hope for woman with poor egg quality.