How many Embryos are Produced in one single IVF?

Number of Embryos in a Single IVF Cycle

In Vitro Fertilization (IVF) has been described as one of the most important medical breakthroughs of the 20th Century. Over 5 million children all over the world have been born using this technology.

What is considered as the ultimate outcome of IVF treatment? Clinical pregnancy is the primary goal. In the beginning, clinicians transferred too many embryos, with the hope that at least one out of them would successfully implant and give a favourable pregnancy outcome. But gradually, over time and with increasing expertise and knowledge on the subject, it was understood that the outcome was related to the number and quality of embryos available for transfer rather than the number of embryo transferred.

When any couple undergoes or plans for IVF, there are a lot of questions that they have in mind. An understanding of the process, the time required, financial requirements, what they need to do for a successful result, are just a few of the many queries that burden their minds. One such question which crosses everyone’s mind is the number of embryos that are produced in a single IVF cycle. There is no single answer to this question, as there are a lot of factors which determine the number of embryos produced in an IVF cycle. Just as no two persons are alike, every patient is not the same.

The number of embryos produced in an IVF cycle are largely dependent on the number and quality eggs or oocytes and the sperm count and its morphology. Other factors which matter are the age of the man and woman, how women respond to the hormonal stimulation, the number of eggs produced in during hormonal stimulation, Body Mass Index (BMI) and other systemic and lifestyle factors.

However, the most important factor which dictates the number of embryos being formed, is the number, quality and the maturity of the eggs retrieved. Usually, in women, after 35 years of age the quality and number of eggs starts declining. So, age of the woman has a definite bearing on the outcome of ovarian stimulation and the number of eggs retrieved. After 35, as the age increases, the ovarian reserve dwindles, and the chances of getting more number of good quality embryos starts declining. As opposed to this, women with polycystic ovarian syndrome (PCOS), are likely to produce more number of eggs, thereby increasing the chances of getting more number of embryos. However, more number of eggs can also mean that the quality of the eggs might be compromised and they may not yield good quality embryos or no embryos at all.

Another point to consider is that, during ovarian stimulation, all eggs are not growing at the same rate, so the timing of oocyte retrieval has to be such that we get the maximum number of mature eggs. Mature eggs are more likely to form good quality embryos, as opposed to immature eggs which may not fertilize at all.
In couples with compromised egg and sperm quality due to age, diminished ovarian reserve, smoking, environmental factors etc. even if one or two good embryos are formed, it is a big achievement; as even a single good embryo can result in a successful pregnancy. As opposed to this, favourable egg and sperm factors in couples facing infertility due to other causes like tubal block, can lead to formation of multiple embryos which can also be kept frozen for future use.

An understanding of the cause of infertility, along with factors like age and ovarian reserve is important to determine and expect the number of embryos being formed in any particular IVF cycle, as this number is always going to be different with each patient.