Fertility preservation has become more and more popular over recent years. We wanted to get the details on exactly what fertility preservation is and learn a little more about the differences between egg freezing and embryo freezing, so we asked an expert: Dr. Creighton Likes.
Dr. Likes is an experienced reproductive endocrinology and infertility specialist (REI) previously associated with Fertility Center of the Carolinas and is a founding physician at the new CCRM location opening later this year in Greenville, SC. In this interview, Dr. Likes addresses common questions about fertility preservation to help you decide if it's right for you and what you can expect.
Dr. Creighton Likes, MD
Berry: Delaying motherhood into your 30s and 40s is becoming more and more common. Can you tell us a little bit about egg freezing as a method of fertility preservation (for example, who is a good candidate, how many eggs is a good amount to freeze, any statistics about the success of fertilizing the eggs in the future when they’re thawed etc.)?
Dr. Likes: Egg freezing has become much more of an option as technology and accessibility have improved tremendously. The earlier a patient can go through the process, the better. This is because both the quantity and the quality of eggs decrease with age. An initial evaluation with blood work (AMH level in particular) and a pelvic ultrasound (follicle scan) would be the first step in order to move forward with an optimal treatment. In regard to number of eggs to freeze, the bottom line is, the more the better. The reason for this is that, on average, it takes 5-6 frozen eggs to eventually have 2-5 usable embryos in the future. If the initial evaluation is normal, the average egg yield in a treatment cycle is 10-20. If the egg yield is low, there can be multiple egg retrievals in order to hopefully obtain a suitable number of frozen eggs for future use.
Berry: Can you briefly tell us what the actual treatment process of egg freezing is like?
Dr. Likes: The treatment process for egg freezing is identical to an IVF treatment cycle. After the initial evaluation there will likely be a “prep phase” lead in, typically with oral birth control pills, and then the “stimulation phase” begins. During the stimulation phase, the patient will do daily injectable gonadotropins (meds to stimulate egg production) and will also have monitoring visits with their clinic that entails an ultrasound and blood work. Based on the findings at the monitoring visit, the medications can be adjusted up or down, if necessary.
Once the follicles are the appropriate size, the patient will be instructed to take a trigger shot (which prepares the eggs for retrieval) and then the egg retrieval will be done ~36 hours after the trigger shot. The egg retrieval is done under sedation and typically only takes 15-25 minutes. The patient is told the number of eggs that day and is discharged home shortly after the procedure. Once in the lab, the eggs are evaluated and the mature eggs (oocytes) will be frozen a few hours after the retrieval.
Berry: Recently, we’ve been asked about embryo freezing as a way to preserve your fertility. What are the differences between egg freezing and embryo freezing? Is one a better option than the other?
Dr. Likes: The process of egg vs embryo freezing is the same (as above). The difference is what happens after the egg retrieval. If the patient is creating embryos, that means there is a sperm source - either a partner or donor. After the eggs are retrieved and in the IVF lab, they are attempted to be fertilized with sperm either by conventional IVF or with ICSI (Intracytoplasmic Sperm Injection). The day after the egg retrieval is day one of embryo development, [on this day] the embryologist will evaluate the eggs and be able to determine how many fertilized. After that, the embryos are typically held in culture in the incubators for 5-7 days and then they are frozen at the Blastocyst stage of development.
When asking about which is a better option, egg vs embryo freezing, the short answer would be that embryo freezing is a bit more “reliable”, meaning, most good quality embryos that are frozen will survive the thaw when the patient is ready to use them. However, if a sperm source is not available, then egg freezing is an excellent option, as discussed above.
Berry: What would you say is the most important thing to know about fertility preservation for someone who is researching their options?
Dr. Likes: Hands down I feel that patients need to be proactive in regard to their fertility and to be their own advocate. Since age is the number one determining factor in fertility, the sooner they get the evaluation process started, the better, even if it is purely for information gathering purposes.
If you are considering egg freezing or embryo freezing, you can always start by talking to your OBGYN or booking a consultation with a fertility specialist to learn what might work best for you. As Dr. Likes said, getting started sooner rather than later is key!
If you want to check out more from Dr. Likes, he shares incredibly helpful content on his Instagram account, @creightonlikesmd.