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Egg Maturity and HCG Trigger: Why Do I Have Immature Eggs?


I’m 39 years old and have done 3 IVFs. During the first two IVFs, half of my eggs were immature. I had 25 retrieved (age 37) the first time, and 16 retrieved (age 38) the next time with 50 percent maturity in both cases. However, I just had an egg retrieval where 15 were retrieved and only 2 eggs were mature. They used generic HCG in this case, and the doc seems to want me to try the transfer the pretty crappy embryos that resulted from this retrieval. He is offering no answers as to why just 2 eggs were mature upon retrieval and the embryo quality was my worst yet.

Does the kind of HCG trigger make a difference? For the second retrieval, I didn’t use generic HCG but Novarel. I think I used Ovidrel for the first trigger. Do you think I have a genetic defect and should be tested? I also think I have some of the signs of PCOS (acne and some sideburn hair that I remove), but doctors don’t think I have PCOS because I have regular periods and am not overweight. Yet, I’ve heard many PCOS women produce immature eggs. Also think I may be insulin resistant and have heard a connection between this and immature eggs as well.

Would appreciate your insight. Emma from California

ANSWER: Hello Emma from the U.S. (California),

Egg maturity at the time of retrieval is based on two things: (1) the size of the follicle when triggered and (2) adequate HCG stimulation.

First, let me answer the HCG question.  If the HCG is an inadequate dosage or not a quality product, then it is possible that the follicle and consequently the egg within, will not get adequate hormonal stimulation to go through the final maturation phase.  Sometimes the egg will not release from the wall and so no egg will be retrieved but otherwise, it would not be mature.  In terms of follicle size, it is usually a requirement that the follicle reach a minimum of 16 mm to insure that the egg within has matured.  Physiologically, as the follicle grows from FSH stimulation, the egg grows toward maturity.  When it reached mature size, the final act is for the HCG or LH which is the physiologic trigger, causes the egg to go through the final phase of maturation and release from the wall.  If the follicle is less than 16 mm, an egg could still be retrieved but it would not be mature.  This is where the “art” and experience of the Physician comes into play.  It is his/her decision as to when the optimal time to trigger is.  The goal, or what should be the goal, is to trigger when the majority of follicles are of mature size but not let it go on so long that you begin losing the larger follicles.  That balance is the key.  In my case, I use 50% maturity as my baseline measure, since follicles tend to grow at different rates.  That is to say, that I strive to have at least 50% of the retrieved eggs to be mature.  In most cases it is much more than that.

You are correct that PCOD patients tend to have a lot of immature eggs but that is because they have so many follicles that result from stimulation.  Where a normal woman might produce 15-20 follicles, a PCOD patient will often produce 30-40 follicles.  Since they develop at different rates, that leads to different maturity levels.  In terms of medication, I favor Ovidrel.  In my experience (22 years), I have had cases where the eggs don’t mature as a result of Novarel or Generic HCG, so I abandoned them.  In addition, Ovidrel is a subcutaneous injection whereas the HCG is intramuscula o, it hurts more.

Good Luck,

Dr. Edward J. Ramirez, M.D., FACOG

———- FOLLOW-UP ———-

QUESTION: Thank you, Dr. Ramirez. There was one more piece of information I forgot to include. Before I started this last cycle, I had been on a three-month dose of lupron. I began stimming exactly three months to the day of my lupron injection, even though I still had hot flashes and only had six follicles to start. Follicles grew from 6 to 8 to 12 the day of the trigger. Normally my number of follicles are in the teens at the beginning of the cycle. I even mentioned this to the doctor and told him that I was still having hot flashes as well. Is it possible that my ovaries were over-suppressed, which resulted in just two immature eggs out of 15?

Thank You,



Hello Again,

Usually the stimulation, if given in adequate dosage, is enough to overcome the Lupton suppression, but I think that your thinking may be right, and that your ovaries may have been suppressed enough so as to not perform as well in the last cycle and the stimulation was not enough to overcome that suppression.

Good Luck,

Dr. Edward J. Ramirez, M.D., FACOG

Monterey, California, U.S.A.

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