The Timing of the Egg Retrieval and Embryo Transfer

The Timing of the Egg Retrieval and Embryo Transfer 

In vitro fertilization (IVF) has been looked at as a standardized process for many years. However, at the CHR, we believe that two critical steps require more personalization than they typically get: the timing of the egg retrieval and the timing of the embryo transfer. Individualizing these two steps can optimize the IVF process and make a difference in treatment outcomes.  

The Timing of the Ovulation Trigger 

For decades, the timing of the ovulation trigger shot has remained largely unchanged since the earliest days of IVF. Most IVF clinics administer the trigger when the lead follicle reaches between 18 and 23 mm in size. This approach has been widely accepted since the early days of IVF and until about ten years ago, we followed the same protocol. 

However, our clinical observations and research began to challenge this one-size-fits-all approach. The patient population at the CHR is generally older than the average IVF population in the United States. As is well established, pregnancy and live birth rates gradually decline with advancing female age, but around age 43, that decline accelerates significantly. 

Through our studies, we identified age 43 as a critical turning point. At this stage, an increasing number of women appear to mature their follicles and the eggs within them more rapidly than younger patients. This suggests that waiting for follicles to reach traditional size thresholds before triggering ovulation may, in some cases, mean missing the optimal window for egg maturity. 

As a result, adjusting the timing of the trigger based on patient age and their ovarian response can help better align with each individual patient, rather than relying on standardized methods.  

The Timing of the Embryo Transfer 

Just as the ovulation trigger timing should be individualized, the timing of the embryo transfer should be tailored to each patient as well.  

At the CHR, we generally favor cleavage-stage (day 3) transfers and fresh transfers over blastocyst-stage and frozen transfers, especially in our older patients. We also don’t believe the idea that embryos are better off if they are frozen and transferred in a later cycle. If you freeze embryos rather than transfer them fresh, you are already accepting some degree of loss in cumulative pregnancy potential.  

For these reasons, the timing and approach to embryo transfer are critical decisions and, like trigger timing, should always be individualized to optimize outcomes. 

Moving Toward Precision Medicine  

The era of applying the same IVF protocol to every patient should be behind us. 

As medicine continues to advance toward precision care, IVF must evolve as well, embracing individualized treatment approaches that reflect each patient’s unique biology.