In-Vitro Maturation (IVM) is a variation of conventional IVF, where the big difference is the collection and use of immature eggs. It’s a relatively new protocol (since about 2008) and clinics are still perfecting the retrieval and maturation of immature eggs and the receptivity of the womb lining for implantation. i In IVM, immature eggs are “matured” and then fertilised alongside the mature eggs that are usually collected. IVM procedures are possible with very little or no drug stimulation before egg collection, especially when women have numerous large eggs in their ovaries (PCO). The low level of stimulation with medications reduces one of the most significant cost of treatment in standard IVF protocols.
When to consider IVM
IVM may be the most suitable option when:
- The woman has a susceptibility to developing ovarian hyper-stimulation syndrome (OHSS)
- The ovaries are polycystic (PCO)
- A couple’s infertility is mainly due to male factors
The IVM protocol
The mature egg is collected from the dominant follicle (as in conventional IVF), but smaller, immature eggs are collected from smaller follicles that develop alongside the dominant follicle each menstrual cycle.
These immature eggs are then placed in an incubator for 24-48 hours, with about 70-80% of them successfully maturing. These eggs are then fertilised, incubated, and transferred to the womb precisely as in conventional IVF.
A human chorionic gonadotropin (hCG) injection is given before egg collection to prevent the follicles from rupturing and encourage them to detach from the follicle wall
When IVM is done with mild stimulation, low levels of FSH will increase the number of eggs that might be collected
Advantages of IVM
- It’s possible to carry out IVM during a woman’s natural menstrual cycle, which avoids the need for medications
- There’s no drug suppression of the cycle (which can cause menopausal symptoms)
- Without FSH medication, the costs are lower, and treatment is more straightforward
- It’s possible to carry out back-to-back cycle treatments
- The natural selection of high-quality eggs (part of a natural cycle) is retained, along with the benefit of retrieving many eggs, with low or no ovarian stimulation
- Clinical pregnancy rates for women with PCO or PCOS have been reported at 30-35% in couples who’d previously been diagnosed infertile (based on about 1,000 cycles of IVM treatment)
Disadvantages of IVM
- The success of natural-cycle IVF/M depends on the availability of smaller follicles in the ovary
- It’s possible that no immature eggs are collected or successfully matured in a cycle
- Not all women are suitable for this treatment
IVM success rates
Some of the success rates reported for natural cycle IVF/M are very encouraging. Pregnancy rates are affected by age, egg reserve, hormone profile and implantation factors, but research involving 410 IVM cycles showed clinical pregnancy rates of: ii
- 40.4% for natural-cycle IVF/M
- 41.3% for IVM alone
- 37.8% for COH (controlled ovarian hyper-stimulation with gonadotropin) (mild drug stimulation)
There were no significant differences in implantation rates between the three groups, and the treatment is considered an acceptable option for over 50% of infertile women.
IVM and PCO
Because the ovaries of women with polycystic ovaries have many large follicles, there’s a higher risk of ovarian hyper-stimulation syndrome with stimulated IVF treatment.
A comparison of clinic results using IVF and IVM shows that:
- 8.2% of women receiving IVF had OHSS
- 0.0% of women receiving IVM had OHSS iii
However, the outcome of the fertility treatment for this study also showed:
- 50.5% pregnancy (and 44.3% birth) rates in the IVF group
- 19.6% pregnancy (and 16.5% birth) rates in the IVM group
IVM appears to be a much safer option than IVF for women with polycystic ovaries, it’s a relatively new technique, and no doubt further improvements will be made.
ii ‘Selection of patients for natural cycle in vitro fertilization combined with in vitro maturation of immature oocytes’ Lim et al, Fertility & Sterility Vol. 91, 4, 2009
iii‘In vitro maturation or in vitro fertilization for women with polycystic ovaries? A case–control study of 194 treatment cycles’ A-S Gremeau et al, Fertility and Sterility Volume 98, Issue 2 , Pages 355-360, August 2012
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