Day 3 embryos are comprised of eight cells while Day 5 embryos have developed to 80-100 cells. If an embryo has survived to Day 5, the chances of a successful pregnancy are significantly higher. This is also a good way to naturally select the strongest embryos to transfer, therefore, our clinic actively practices Day 5 embryo transfers.
On occasion, a patient’s embryos may develop slower than expected. In these rare cases, the embryologist may choose to culture the embryos to Day 6 which will allow the embryos to grow to an appropriate size for transfer.
This topic is a very common debate and often people think that fresh is better because it is more natural. The problem is that stimulating the ovaries to grow several eggs at one time is an unnatural process. The medications and hormone levels associated with induced ovulation affect the lining of the uterus, the receptivity of the uterus, and the capacity to carry a pregnancy. In brief, the woman’s body is not in optimal condition to accept an embryo.
Our clinic prefers a method known as ‘freeze all’. This means that all embryos will be frozen on Day 5 or Day 6 and stored until the patient’s body recovers from the stimulation medication. When the woman’s hormones have returned to regular levels, a frozen embryo transfer cycle can be started which prepares the woman’s uterus to accept an embryo. Your doctor will help you decide on your preferred method.
Since there is a significant increase in the risks associated with multiple pregnancies, our ultimate goal is to have each patient’s treatment result in the live birth of a single healthy baby. This often requires the transfer of only one single embryo. We acknowledge that every case is different and may be affected by other factors such as age or repeated failures, therefore, our physicians and embryologists will work with you to determine the best and safest number of embryos to transfer based on the recommendations of our preferred organization.
If you are receiving treatment under a government funded IVF cycle, there are strict rules that dictate the number of embryos you are allowed to transfer and our clinic must follow these rules. These restrictions will be discussed with you at the appropriate time by your physician.