In vitro maturation (IVM) is an advanced assisted reproductive technology (ART) designed to help individuals achieve pregnancy. This technique involves retrieving immature eggs from the ovaries and maturing them in a specialized laboratory environment. A primary goal of IVM is to reduce or eliminate the extensive hormone injections typically used in conventional in vitro fertilization (IVF) cycles. This approach offers a gentler alternative for patients seeking fertility treatment by shifting a significant part of the egg maturation process outside the body.
The In Vitro Maturation Procedure
The IVM procedure begins with minimal or no hormone stimulation. Ovarian monitoring, using ultrasounds and blood tests, determines the optimal time for egg retrieval. Unlike traditional IVF, where mature eggs are collected, IVM specifically targets immature eggs from small ovarian follicles. These eggs are collected through a minor surgical procedure, typically using transvaginal ultrasound guidance to insert a fine needle into the ovaries and aspirate the follicular fluid. Medication is provided for patient comfort.
Once collected, the immature eggs are transferred to a specialized laboratory. They are placed in a nutrient-rich culture medium to support their maturation. This process usually takes 24 to 48 hours, allowing the oocytes to reach the metaphase II stage, which is necessary for fertilization.
After maturation, the now-mature eggs are fertilized, commonly through intracytoplasmic sperm injection (ICSI), where a single sperm is injected into each egg. The fertilized eggs develop into embryos in the laboratory over several days. One or more healthy embryos are then transferred into the uterus.
Who is a Candidate for IVM?
In vitro maturation offers a suitable option for specific patient profiles seeking fertility treatment. Women with Polycystic Ovary Syndrome (PCOS) are often candidates. Their ovaries contain many small follicles, making them susceptible to Ovarian Hyperstimulation Syndrome (OHSS) with conventional IVF’s intense hormonal stimulation. IVM significantly reduces this risk by retrieving eggs before extensive stimulation.
Cancer patients requiring urgent fertility preservation also benefit. They often need to begin gonadotoxic treatments quickly and cannot delay for prolonged hormone stimulation, or their medical condition may contraindicate high estrogen levels induced by conventional IVF. IVM allows for quicker egg retrieval with minimal hormonal exposure, enabling them to proceed with cancer treatment sooner.
Additionally, women with a history of hormone sensitivity or resistance, or those with empty follicle syndrome where no eggs are retrieved despite stimulation, may find IVM a beneficial alternative.
Key Differences Between IVM and IVF
In vitro maturation and traditional in vitro fertilization differ significantly, primarily concerning ovarian stimulation and egg maturity at retrieval. Conventional IVF protocols use high doses of hormonal medications to stimulate the ovaries, producing multiple mature eggs inside the body. This ensures eggs are fully developed before retrieval.
In contrast, IVM requires minimal or no hormonal stimulation, collecting immature eggs directly from the ovaries. The maturity of the eggs at the time of retrieval is another distinct difference. For IVM, immature eggs are retrieved and then brought to full maturity in a specialized laboratory setting. This difference results in a significantly lower risk of Ovarian Hyperstimulation Syndrome (OHSS) in IVM cycles, a complication associated with high hormone levels in IVF, particularly for women with PCOS.
Moreover, IVM cycles generally have a shorter overall duration compared to IVF due to reduced stimulation. Fewer medications also contribute to potentially lower treatment costs for IVM.
Success Rates and Outcomes
Historically, IVM success rates have been lower when compared to conventional in vitro fertilization, but recent advancements are steadily improving these outcomes. Live birth rates for a single IVM cycle are around 32%, compared to IVF’s average of 40%. However, optimized protocols, including a “freeze-all” approach and subsequent frozen embryo transfer, show IVM live birth rates can approach traditional IVF. Some reports show cumulative live birth rates of 39.3% for IVM compared to 49.8% for IVF in specific patient groups.
Several factors influence IVM effectiveness, including patient age and infertility cause. Younger patients and those with more retrieved oocytes tend to have more favorable outcomes. The expertise and specific protocols of the embryology laboratory also play a substantial role in embryo maturation, fertilization, and development. While the live birth rate may still be slightly lower than IVF, IVM offers a valuable option, especially given its reduced risk of OHSS and lower medication burden.