Ovarian Reserve and Egg Freezing

Most women go through life without any knowledge about their fertility potential. Many women delay pregnancy until a more ‘convenient time’, mostly in pursuit of building a career, education, etc. By the time ‘Mr Right’ shows up, their fertility potential may be reduced, or already gone.

What is Ovarian Reserve?

Ovarian reserve refers to the remaining eggs a women has for the future. Age is the universally known marker for eggs quantity, ie, the older a woman gets, the less eggs she would have left. But what is not known is that this fall of egg number is not consistent in every woman. There are women who have ‘run out’ of eggs even in the 30s (premature ovarian failure, rare), and there are those who are still having menses even at 55 years old (rare).

The total number of eggs a baby girl is born with is already predestined even whilst growing inside her mother’s womb. At birth, a baby girl may have 200,000 primordial oocytes (immature eggs). However, many of these ‘oocytes’ undergo degeneration. By the time her menses start, the number of primordial oocytes have dropped to 10,000 – 30,000. These eggs are then lost (during menstrual cycle) constantly until menopause, when they ‘run out’.

The number of eggs remaining depends on a few factors:

1. The number of eggs a woman started with (at birth). Genetics may play a part. If her mother reaches menopause late, she will likely have more egg reserves. There are certain genetic conditions that drastically reduces number of eggs available, eg, Turner Syndrome
2. Diseases that involve the ovaries, will destroy ovarian tissue (and therefore eggs too), eg, endometriosis (blood cyst), or auto-immune diseases that effect the ovaries.
3. Surgery that involve ovaries, eg, cyst of the ovaries. Surgery will inevitably remove good ovary tissue, along with diseased tissue.
4. Certain types of chemotherapy, radiotherapy will drastically reduce the number of eggs.

How about Egg Quality?

Essentially, egg quality refers to possibility of chromosomal abnormalities (aneuploidy) in the eggs produced. This again, is affected by age. This is why miscarriages rates increase after the age of 35 and baby with problems, such as Down Syndrome also increase with age.

Egg quality can also be affected by the environment, eg, toxins, radiation, heavy metal, alcohol, cigarette smoking, etc. There are cases of young women in their 20s, with good number of eggs, but with poor egg quality (rare).

How to test for Ovarian Reserves?

There are a few ways to test for ovarian reserves (quantity).

1. Baseline FSH
   • Done on Day 2/3 of the cycle
   • Commonly available test
   • The higher the result, the nearer the women is to menopause
   • Not very accurate, as values change from laboratory to laboratory, and change even during different times of the day.
2. Antral Follicle Count. AFC
   • Counting the number of small antral follicles (2-9mm diameter) via transvaginal scan.
   • A good indicator of available eggs
   • Not always done routinely during gynaecological check-up.
3. Anti-mullerian hormone, AMH levels
   • Blood test, measures hormones produced by primordial follicles (ie, immature egg in the ovaries)
   • The higher the levels, the more ‘eggs are available’
   • Mostly utilised by fertility doctors

How to test for egg quality?

Egg quality is harder to test. The tests above are not reliable for egg quality.

1. Age
   • In general, age is still the best indicator of egg quality
   • A 45 year old, may have high AMH levels, and high antral follicles, but most of her eggs are of poor quality
2. Response of ovaries to fertility medications
   • During fertility treatment, if eggs grow well, then it is presumed to be ‘good quality’. But if the eggs only grow with very high doses of medication, then the eggs may be of poorer quality.
3. Assessment during IVF cycle
   • Not an actual test, but as a form of treatment.
   • During IVF, the eggs produced will be observed over a few days from fertilisation, Day 1, up till Day 5. The morphology (shape) of the embryos can be objectively seen, and this will give some clues as to why pregnancy has not occurred previously

What happens when poor quality eggs are ovulated every month?

The eggs

1. Does not fertilise
2. Fertilise, but does not develop well enough to implant, or stick to the womb
3. Implant, but is not ‘healthy enough’ to continue fetal development, resulting in miscarriage

Do women need to check for their Ovarian Reserves even if there are not currently trying to get pregnant?

Women of reproductive age should have an idea of their ovarian reserves, especially if they are interested in having children “in the future”, eg, delay until their 30s (NOT 40s).  Testing for ovarian reserves is very specific, and is usually not done in routine examinations by a gynaecologists unless specially requested. Having regular menses, normal pap smear, normal ‘yearly medical blood tests’, does NOT equals having good ovarian reserves.

Advice –

1. If a woman in her early thirties have good or normal ovarian reserves, she can probably post-pone getting pregnant for a few years.
2. But if she has low ovarian reserves expected for her age, then the advice is to start a family as soon as possible, more so for women above 35 of age.
3. If a women is more than 37, and has low ovarian reserves, better find a ‘good man’ soonest and get pregnant fast!

 

Oocyte Cryopreservation

What is Oocyte Cyropreservation?

Oocyte Cyropreservation or ‘Egg freezing’ is the process of storing ‘mature’ eggs for the future when a women wishes to get pregnant at a later date. It’s getting a lot of attention in the media because Facebook and Apple are offering ‘egg-freezing’ as a benefit to their female employees.

A women who wants to freeze her eggs will have to go through a process almost similar to what IVF patients go through, ie, daily injections for 10-14 days, and the eggs retrieval process (which is usually under anaesthesia). The eggs are frozen, and stored until needed, whereby the eggs will be thawed and fertilised with the partner’s sperms and replaced back into the womb.

What are the reasons for Cyropreservation?

1. Cancer
   • Women of reproductive age are not spared from having cancers (eg, leukemia, breast cancer, brain cancer, etc). Successful treatment of cancer may include powerful medication, eg, chemotherapy and radiotherapy, which are also toxic to the oocytes (eggs). Cancer treatment sometimes cause premature menopause or severe reduce a woman’s ovarian reserves. With modern cancer treatment, a woman may overcome cancer, only to face fertility problems later on.
   • Egg freezing is an option if a cancer patient wants to have children in the future (Fertility Preservation). The process can be done within a few week of the cancer diagnosis before cancer treatment starts. When the cancer is cured, she can use the frozen eggs to get pregnant.
2. Social Reasons
   • With more awareness on their ‘biological clock’ ticking away, more women are choosing to have egg freezing at a younger age, eg, late 20s or early 30s (when the eggs are relatively ‘good’ quality).
   • Thus, they can focus on their career, education, etc, before finally settling down and start a family.

How long can the frozen eggs be stored before the ‘quality’ drops?

From the scientific point of view, there is no time limit how long these eggs are frozen. The important aspect is the technology used to freeze the eggs. The latest advancements of using ‘ultra-rapid freezing’ or vitrification (versus the older technology of ‘slow freezing’) have increased the survival rates of frozen eggs to more than 90% (from 50-60% previously in the early 2000s).

I am 38 years old, can I still freeze my eggs?

Egg freezing can be done for any age. However, the quantity and (more importantly) the quality of eggs frozen will not be the same for someone who is 38 years old, as compared with someone at 28.

In general, there is a rapid decline in fertility in women after the age of 35 years old, mainly due to lower quality among remaining eggs. These effects, unfortunately, will NOT be improved by freezing the eggs.

Therefore, the ‘best’ age for women to freeze their eggs, is when they are younger, preferably less than 35, even better if less than 30 years old.

 

Dr Chong Kuoh Ren
April 2016

 

Infomation in this article have been compiled from various sources, including: AFC, Chicago, here