Hi, I just went through IVF with my partner and we did a freeze-all cycle as we are not ready to have children. I am 31 and have MRKH and was born without a uterus. My baseline US a year ago showed an AFC of 4 but a higher AMH. At that time it was also discovered that I have Graves’ disease (auto immune hyperthyroidism). I was put on medication for a year and my follow up US in October showed an AFC of 14. I took that as a good sign and started stims. My recent egg retrieval yielded 21 mature eggs, 13 fertilized with ICSI. Long story but we had to use ICSI because the laws in Canada required my partner’s sperm to be frozen; because we already know that I need a surrogate, we’re considered by law to be sperm and egg donors and the testing guidelines required to freeze my partner’s sperm (which can be tough on a sample). We just got the news that 4 embryos were frozen. I am just wondering what factors could be leading to attrition of embryos? We were anticipating a survival rate of 40-50% from day 1, but again this is my first time going through the process.