Types Of Embryos For IVF Procedure – Factors To Look Out For!

Types Of Embryos For IVF Procedure

Embryos are of great significance when it comes to infertility treatments like IVF procedures. In fact, choosing the appropriate embryo to implant into a woman’s uterus is one of the most important and difficult steps in the procedure. Often, we say that the inability of women or men to procreate is the reason for infertility. But, what causes the condition? 

We cannot simply drag our attention to a single reason, whereas infertility is one such condition that has around ten or more reasons. However, the most important one is the role of healthy eggs and sperm. In fact, the quality of your eggs and sperm can support and oppose fertility. Not only that quality but the quality is also measured to identify how fertile you are.

When you have a combination of both, it is more likely that you will get to experience pregnancies as well you will receive a healthy baby. This is why doctors often recommend that women should conceive in their 20s and men should impregnate their women before their 40s. In most cases, fertility decreases as you age. What happens is the quality and quantity of both eggs and sperm are affected as you grow old.

This may cause complications for both the mother and the child. To the worst, it might also lead to genetic disorders in the kids or miscarriage. However, age is not only the factor that contributes to the overall health of the embryos. In this article, we are going to discuss the types of embryos used in IVF procedures so that you know what you can do to improve their quality to enhance the chance of your pregnancy. 

Factors Affecting The Quality Of An Embryo 

There are several factors that decide the quality of an embryo. To begin with, it is the quality of parent germ cells that is responsible for the embryo quality. If they are free of pathologies then you can expect a 25% success rate from the procedure. 

Secondly, the knowledge and experience of the embryologist should be carefully examined before going into the treatment plan. Embryos are supposed to be kept in a suitable area where it is not disturbed. Even the slightest mistake can stop the embryo growth resulting in the failure of the procedure.

Factors Affecting The Quality Of An Embryo 

There is one more factor that affects the quality of an embryo, however, it can be controlled neither by the patient nor by the doctor because it is a defect in the chromosome. In such cases, more attention is required so as to ensure IVF ends up in pregnancy. Often, doctors check the quality of embryos every day so that there comes no flaws on their side. 

How To Differentiate Quality Embryos From Non-Quality Ones? 

Before the retrieval of embryos, women are provided with ovulation induction medicines that help produce multiple eggs in a month. These eggs are fertilized by sperm in a laboratory. In order to increase the chance of pregnancy, doctors often keep multiple embryos to choose the best among them. Now, the question is how the doctors choose the best embryo to implant into a woman’s uterus. 

First of all, each embryo is carefully taken out of the incubator and is observed in a microscope every day, or several times a day to monitor the changes. The embryo is not kept in the incubator for a long period as it is sensitive to the external; environment. 

While checking the quality of embryos, experts look for the following factors; 

  • Size and the number of cells- size, and number of cells increase day by day. The first one to reach the appropriate size is selected for the procedure. 
  • Quantity of non-nuclear cells- The number of non-nuclear cells should not be more than 25% of the total amount.
  • Intracellular inclusions- there should not be any intracellular inclusion as they are said to destroy the cells
  • Overall appearance: Embryos must be of perfect size, and shape and free from any kind of deformations 

Types Of Embryos For IVF Procedure 

During the incubation period, you cannot classify an embryo according to its quality as all embryos look quite similar in this stage. However, a doctor is supposed to understand which of the embryos before him are viable and which are not.

But, due to the confusion, experts wait until the day of embryo implantation to finally classify them. By doing this, the process becomes even simpler than before. They usually wait until the day of embryo transfer to make sure that the embryos are suitable to be classified.

Normally, an embryo transfer is carried out on the fifth day of fertilization. So, by the time, the embryos are expected to develop changes which enable the doctors to classify them according to their ability to implant on the uterus and development potential. 

Until the day of transfer, the doctors note the growth and development of the embryos by assigning them a quality code every day. The quality code is a combination of numbers and letters where the first two numbers indicate the development stage of the embryo and the remaining 2 letters denote the formation of the fetus and the chance of attachment to the uterus respectively. 

The numbers are classified among themselves. They are points starting from 1 to 6, where 1 stand for an early blastocyst, the foremost stage of an embryo, and 6 stands for a completely matured embryo that is usually considered for transfer.

Similarly, the letters also carry specific meanings such as A refers to good quality embryos where as D is given as a quality score to embryos that are of poor quality. This information is recorded by the doctors in their embryo protocol, a document where data regarding the changes in the embryo are recorded from day 1 to the day of embryo transfer. 

However, no doctors draw conclusions about the potential of an embryo on the second or third day of observation. This is because often a blastocyst turns into a matured embryo within days which compels the doctors to change their preconception. 

Read More:- Effective Fertility Treatments For Different Causes Of Infertility

Understanding The Growth Of An Embryo 

The embryologist initially collects multiple eggs and chooses the mature ones to fertilize with sperm. The fusion normally occurs after 15 hours, however, the day of egg and sperm fusion is not counted as day 1, instead, the days are counted starting from the next day. 

Understanding The Growth Of An Embryo

  • Day 1– Formation of the zygote 
  • Day 2– Blastomeres are usually formed after the second day of fertilization. Therefore, doctors begin to assess the quality of an embryo from the second day via the size and shape of the blastomeres formed. 
  • Day 3– The cells are divided and by now at least 6-8 cless are formed. During the third day, doctors are capable of determining the embryo quality based on the degree of fragmentation as well as the shape and size of the blastomeres. Moreover, in some cases, embryos are transferred on the third day as it reaches maximum maturation.
  • Day 4– The fourth day is often considered to be the beginning of the morula stage where an embryo is meant to have 10-14 cells. By now, a cavity is formed inside the embryo, which is commonly called a blastocyst. 
  • Day 5-6 – It is the blastocyst stage during which an embryo is well developed to implant into the uterine wall. The covering of an embryo ruptures over time as the blastocyst grows. Following this, the embryo attaches itself to the uterus and continues to grow. 

Advancements Made To Understand The Embryo Quality 

Recently, a new technology named time-lapse microscopy was introduced where the embryos are monitored continuously so as to identify and predict the potential changes of the embryo. This method works on the principle of the automatic photographic program which is attached to the incubator.

This enables the embryologist to understand the development graph of the embryos without taking them out of the incubator. This way, the embryos are less likely to interact with the outer environment which causes harm. In other words,  time-lapse microscopy eliminates the risk of embryo damage caused by the environment and it also helps to evaluate the dynamics of the embryo development as well. 

Read More:- Do You Need Some Rest In IVF Procedures? Discover The Truth


Embryos are of different types and it is classified based on their qualities including their potential to implant on the uterine wall, and complete fetal growth throughout the pregnancy period. Since the entire process of embryo transfer depends on the quality of the embryo it is important to take medication that helps achieve it. Also, you should make sure to consult an efficient embryologist who has met with many such cases in their career.

The qualification of the embryologist is important because it is also one major factor that contributes to the success of an embryo transfer. Therefore, be wise when you take a step ahead and also make sure that you are doing your part well to maximize the chances of a healthy pregnancy. 


Leave a Reply

Your email address will not be published. Required fields are marked *