Advancing the Accuracy of Ovulation Trigger Timing for HIER

Advancing the Accuracy of Ovulation Trigger Timing for Highly Individualized Oocyte Retrieval (HIER) 

It has been more than 40 years since the first IVF baby was born and today, millions of babies are born using assisted reproductive technology. Throughout the years, new studies and research have been conducted which contributes to the advancement of reproductive medicine. One topic that has become popular is the process of how follicle development is monitored and how to determine the timing of the egg retrieval.  

The Traditional IVF Process 

In nearly every IVF clinic, cycle monitoring relies on ultrasound measurements of a patient’s follicle size. When the largest follicle reaches approximately 18mm to 23mm, a medication called the trigger injection is administered. Based on decades of experience, we know that ovulation typically occurs about 36 hours after the trigger. Therefore, most clinics will schedule the egg retrieval earlier, around 34 hours after the trigger. This timing has become routine practice and works for many patients, but it is not optimal for every patient.  

The Effect of Age 

A biological process that challenges this standard approach is luteinization. Luteinization is the maturation of the follicle and egg in preparation for ovulation. As women age, this process of maturation tends to occur earlier and earlier. This means that these patients’ eggs may reach full maturity sooner, and that waiting for the standard trigger timing may be too late for them.  

This age-related shift is subtle, but it may have significant consequences. For example, an egg that matures too early or too late can compromise fertilization, embryo development, and ultimately pregnancy outcomes. 

One Size Does Not Fit All   

At the Center for Human Reproduction (CHR), where our patient population is significantly older than at most IVF clinics in the United States, this topic of earlier egg retrievals for our patients became very important. We learned how important the follicle size determination is to the success of the retrieval, so our care team customizes the timing of each treatment plan based on the individual patient’s needs. 

Highly Individualized Egg Retrieval (HIER)  

HIER is based on the understanding that follicle maturity is a biological process, not just a measurement. Instead of treating all patients with the same protocol, the process of HIER tailors the timing of the ovulation trigger and egg retrieval to the individual patient.  

Key principles of HIER include: 

• Recognizing that follicular maturation occurs earlier with advancing age 
• Adjusting trigger timing to retrieve eggs before over-maturation occurs 
• Maximizing the number of developmentally competent eggs, not just the number retrieved 

In practice, this means earlier, personalized egg retrievals for patients who need them, particularly older women.  

At CHR, we are excited for the future advances in reproductive medicine, and we remain committed to meeting our patients exactly where they are in their fertility journey.