Why is egg count important in IVF? The expert told
A woman ovulates an average of 400 times after the first menstrual period until menopause, but the probability of pregnancy at each ovulation is no more than 25%, even for the young age. In other words, only one in four couples who want a child each month can get pregnant. After the 1940s, this probability drops below 5%. There is also the possibility of pregnancies resulting in miscarriage. Although the chance of a pregnancy ending in miscarriage is about 15% at a young age, it increases with age.
The main reason for this is that not every egg is genetically normal. This situation has been understood through the genetic analyzes performed on the eggs during IVF applications. The likelihood of eggs being genetically normal decreases with age. While 6-7 out of 10 mature eggs from a 35-year-old woman are normal, this figure drops below 5 by age 40. It takes 8-10 eggs to find a normal 44 year old egg.
In a woman’s normal cycle, 1 egg matures and hatches every month. If IVF had been done without medication, the chances of pregnancy with this 1 egg would have been very low. For this reason, attempts are made to increase the number of eggs during IVF. From the beginning of menstruation, injections are given and the growing eggs are monitored by ultrasound. In fact, those on ultrasound are round sacs of fluid. These are called follicles. Each follicle contains one egg. When the follicles are large enough, they are aspirated and the egg is sought.
Op.Dr.Numan Bayazıt continues his words as follows;
From this stage it is better understood why a large number of follicles/ova is desired. The probability of eggs coming from each aspirated follicle is about 80%. In other words, some of it comes out empty or the egg doesn’t come. Not all incoming eggs are mature. About 7-8 out of 10 eggs are of good quality to use. Not all eggs are fertilized. Here, too, about 20% is lost. Not all fertilized parts divide and develop beautiful embryos. About half of fertilized eggs stop developing at some point. Any embryo that grows up to the stage we call blastocyst, i.e. seemingly high quality and transferred, cannot attach. On average, one in 2-3 has the genetic structure to become pregnant.
For all these reasons, having a large number of eggs during IVF is a great advantage. We can say that the ideal number is 12 – 13, but a woman with a small number of eggs should not be discouraged. This results in a pregnancy with 1 quality egg. Especially before the age of 40, we have a high chance of getting pregnant, even if there are few eggs. Especially after the age of 43, the quality of eggs decreases and their genetic structure deteriorates. In fact, at least half of the couples who register with us have fewer eggs than desired and most of them are older than 40 years. In this case, we try to increase the chances of pregnancy by collecting eggs over several months and making as many quality embryos as possible. This is called the pool system. In a sense, we are trying to solve the quality problem by increasing the number.