After embryos are created in the IVF lab, the next step is preparing for embryo transfer. Embryos are typically frozen at the blastocyst stage (Day 5, 6, or 7) and transferred in a subsequent cycle following egg retrieval.
Timing of Embryo Transfer
The transfer can occur in the cycle immediately following retrieval or months to years later. Importantly, the success of frozen embryo transfer remains consistent regardless of how long embryos have been frozen. The age of the person at the time of egg retrieval is a primary factor influencing outcomes, rather than the age of the uterus.
Treatment Protocols: Medicated vs Natural
When preparing for embryo transfer, two main treatment protocols are used:
1. Medicated Cycle:
In a medicated cycle, medications are administered to build the uterine lining to support embryo implantation. This process typically takes 3-5 weeks:
- Estrogen Administration: Various forms of estrogen (oral, patches, injections, vaginally) are given over 12-14 days to gradually thicken the uterine lining (at least 7mm thick).
- Progesterone Supplementation: Once the lining is ready, progesterone is administered (vaginally or intramuscularly) to prepare for embryo transfer. The transfer is timed based on specific progesterone administration days.
Benefits: Predictable scheduling of embryo transfer with fewer monitoring appointments.
2. Natural Cycle:
In a natural cycle, hormonal processes of the natural ovulatory cycle are utilized to prepare the uterine lining:
- Hormone Utilization: The body’s natural hormones are used to grow the uterine lining as a follicle (egg) develops.
- Trigger Shot: When the body is ready to ovulate, a trigger shot is administered to induce ovulation and release progesterone.
Benefits: Requires less hormone supplementation, though not suitable for patients with irregular ovulatory cycles.
Choosing the Right Approach
Both medicated and natural cycles have comparable pregnancy success rates. It’s crucial to discuss both options with your doctor to determine the best approach for your individual circumstances.
By understanding these processes, you can make informed decisions about your fertility journey. For more personalized guidance, schedule a consultation with your healthcare provider to explore the most suitable path forward.
