During this event, Dr Halyna Strelko, Chief physician, Reproductive specialist at IVMED, Kiev, Ukraine, explained what modified agonist, mild-stimulation and antagonist protocols mean and when they should be indicated.
The primary objective of controlled ovarian stimulation, regardless of the protocol used, is to achieve high-quality eggs, successful fertilization, and an increased likelihood of pregnancy. It is worth noting that only 23% of all embryo transfers, as per extensive statistical data from organizations like ASRM, ultimately result in delivery. This underscores the importance of the number and quality of eggs obtained during the stimulation process.
The probability of achieving a successful pregnancy depends on factors such as the number of eggs retrieved and the woman’s age. For instance, a 35-year-old woman with around 20 eggs has a 70-80% probability of pregnancy, while a woman of advanced reproductive age with 30-40 eggs may have only a 20-30% chance. Therefore, obtaining a sufficient quantity of high-quality eggs is crucial.
The probability of having at least one baby born depends on the number of eggs and the age of women.
The number of eggs obtained during controlled ovarian stimulation is influenced by the anti-Müllerian hormone levels, a reflection of the number of follicles in a woman’s ovaries. Body mass index (BMI) also plays a role, as the same dosage of medication can result in different concentrations in patients with varying BMIs. Additionally, individual sensitivity to the medications may vary, making some protocols more effective than others.
There are different protocols available for controlled ovarian stimulation, ranging from long agonist protocols to antagonist protocols. The choice of protocol can be complex for both doctors and patients, as they attempt to understand the reasoning behind a particular selection.
Controlled ovarian stimulation or IVF treatment involves four main components: gonadotropins (FSH/LH), preventing premature LH elevation, triggering final egg maturation, and embryological aspects such as monitoring follicle development and fertilization rates.
Historically, the importance of preventing premature LH surges became evident through research conducted in the 1970s. The use of agonists and antagonists, which influence LH levels, has since become a critical aspect of IVF protocols. Agonists stimulate FSH and LH initially but then inhibit their production, resulting in more uniform follicle development. Antagonists, on the other hand, rapidly block LH production, but this may not guarantee uniform follicle development.
Agonists protocol initially produce a “flare-up” effect before inhibiting LH production, while antagonist protocol lack this initial surge. This flare-up can sometimes lead to follicle cysts, necessitating more time for LH suppression. The timing of LH decrease is quicker with antagonists.
Comparative studies have shown that while agonist protocol may provide a more homogeneous cohort of growing follicles in women with normal ovarian reserve, there is often little difference in embryological parameters such as egg quantity and quality. However, agonist protocol tend to lead to longer stimulation durations and a higher risk of ovarian hyperstimulation syndrome (OHSS), especially in women with polycystic ovarian syndrome (PCOS).
In contrast, short antagonist protocols have become the preferred choice for many doctors due to their shorter duration, reduced cost, and lower risk of OHSS. However, they may not be suitable for fresh transfers when agonist triggering is used, as it could lead to unfavorable outcomes.
For women with low ovarian reserve, minimal stimulation protocols may be considered to reduce the number of FSH injections and costs. These protocols, including natural cycles, are most appropriate for women with poor ovarian response, as they tend to yield similar results with fewer complications.
In the world of ovarian stimulation, one size does not fit all. Customization is key.
In conclusion, the choice of ovarian stimulation protocol depends on factors such as ovarian reserve, previous responses, and the risk of OHSS. Short antagonist protocols are currently the standard due to their advantages in terms of cost and OHSS prevention, but the specific protocol chosen should be tailored to each patient’s unique needs and circumstances.
