In Vitro Maturation of Oocytes (IVM) in Assisted Reproduction

By (gynecologist), (embryologist) and (invitra staff).
Last Update: 02/17/2021

In vitro oocyte maturation (also known as IVM, or IVM) is a procedure in which immature eggs mature in vitro, i.e. in the laboratory.

To perform this procedure, the most common is that the patient does not undergo a hormonal treatment of ovarian stimulation (if she receives it is at low doses) and this is one of its main advantages.

However, IVF laboratories do not perform IVM routinely and can be thus considered an experimental technique.

Definition of in vitro maturation (IVM)

In vitro maturation is an assisted reproductive technology by which immature eggs are matured in the laboratory until they reach the stage of maturity, also known as metaphase II.

The IVM process consists of incubating the immature oocytes for a period of time that usually ranges from 24 to 48 hours in a culture medium with controlled conditions.

The main difference compared to classic IVF cycles is that in IVM the patient does not receive (or receives at very low doses) the previous hormonal treatment. Therefore, IVM does not require ovarian stimulation, unlike regular IVF cycles.

This is one of the main advantages of IVM, as it minimizes the risk of ovarian hyperstimulation syndrome that can occur as a consequence of ovarian stimulation.


IVM is a technique that avoids ovarian stimulation and thus reduces the risk of ovarian hyperstimulation. Therefore, some of the situations in which IVM would be indicated are the following:

  • Women with polycystic ovarian syndrome (PCOS) or polycystic ovaries. IVM is suitable as a fertility treatment for PCOS, as these patients have a high follicle count (the structures where the eggs are located in the ovary) and a higher risk of ovarian hyperstimulation with conventional IVF.
  • Patients at risk of ovarian hyperstimulation or who wish to avoid ovarian stimulation to reduce the discomfort and costs associated with medication.
  • Fertility preservation. IVM is an alternative for patients who cannot undergo ovarian stimulation because of a hormone-dependent tumor or because they should not delay the start of cancer treatment. If ovarian stimulation can be performed, IVM of immature oocytes can increase the number of oocytes available for preservation. In addition, IVM can also be performed in conjunction with ovarian tissue preservation.
  • Low responder patients. In these patients, it is common to cancel a classic IVF cycle (with ovarian stimulation) due to low response, but obtaining immature oocytes and their IVM can be an alternative to cancellation.

Another option for patients with low response is to perform a "rescue" IVM. In this case, the cycle begins with the ovarian stimulation of a classic IVF cycle. All eggs are collected by ovum pick-up and IVM is performed on the immature oocytes to "rescue" them. The aim is to add them to the oocytes already obtained in a mature state in order to increase the chances of gestation of these patients.

Advantages of IVM

The IVM technique offers a number of advantages that have been mentioned throughout the article and are summarized as follows:

  • It does not require ovarian stimulation, thus reducing the risk of ovarian hyperstimulation syndrome.
  • Reduces discomfort, costs and time in a fertility treatment.
  • It offers an alternative for preserving fertility when ovarian stimulation is to be avoided.


Currently, IVM is very restricted to special cases. The following are some of the reasons why IVM has not become popular:

  • It is considered an experimental technique.
  • It is not optimised because some of the problems it was supposed to solve, such as ovarian hyperstimulation, can be addressed in other ways.
  • There are no realiable results to support the use of IVM versus classic IVF in patients with PCOS.
  • It presents worse results in assisted reproductive technologies and a higher rate of miscarriage.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

In general, the obstetric and perinatal outcomes of babies born after IVM are good. However, there are few studies and, moreover, they follow-up the newborns only for a short period.

For all these reasons, IVM is not currently an alternative to classic IVF in cases where ovarian stimulation is not recommended. On the contrary, IVM does have a lot of potential in fertility preservation.

FAQs from users

What are the benefits of in vitro maturation of oocytes?

By Elena Santiago Romero M.D. (gynecologist).

IVM (In Vitro Maturation) of oocytes is a technique that has been known for more than 20 years, but its clinical application remains very limited. The pregnancy rate results when IVM is applied are still worse than with IVF.

However, there are some cases where IVM can provide advantages over IVF:

  • To optimize the performance of patients with low response. There are cases in which women respond less than expected to ovarian stimulation, so there are small follicles that do not grow with medication. These follicles can be aspirated along with the rest of the large follicles on the day of the puncture resulting in obtaining immature oocytes that could be matured in vitro to obtain more embryos after IVF.
  • For women to whom the administration of gonadotropins for ovarian stimulation is contraindicated..
  • For patients with polycystic ovaries and high risk of ovarian hyperstimulation using gonadotropins.
  • For oncologic patients or patients with other pathologies that require urgent fertility preservation.

In the cases mentioned above, IVM is becoming more important, since it would allow us to increase the number of oocytes to be preserved without having to wait longer and without having to undergo more hormonal treatment before proceeding with the treatment of the disease.

Is in vitro maturation a good option for women with PCOS?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Women with polycystic ovarian syndrome (PCOS) may consider IVM as a possible option.

PCOS patients have a higher follicle count and also an increased risk of ovarian hyperstimulation syndrome.

Since the IVM technique does not require ovarian stimulation, the risk of hyperstimulation is minimized. This makes IVM a perfect fit for the treatment of patients with PCOS.

However, there is not enough evidence to recommend IVM over conventional IVF treatment for PCOS patients. In addition, there is also no clear evidence showing better results in terms of pregnancy rates of IVM versus conventional IVF in PCOS cases.

Is in vitro maturation of oocytes successful?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

In vitro maturation of oocytes is successful, but it is less successful than in conventional IVF/ICSI cycles.

In the latest SEF National Activity Registry Report (Registro Nacional de Actividad 2021-Registro SEF) it is reported that only 5 IVM cycles were initiated during 2021, of which 3 had transfer and there was 1 gestation (33.3% of gestations by transfer) and 0 deliveries.

Imagen: Pregnancy rate with oocyte maturation

In the case of IVF/ICSI of fresh own oocytes, 46,224 cycles were initiated during that same year, 18,454 transfers were performed resulting in 6,353 gestations (with the percentage of gestations by transfer being 34.4 %) and 4,656 deliveries (25.2 % of deliveries by transfer).

Suggested for you

We have discussed ovarian hyperstimulation syndrome throughout the article. Here you can learn more about this topic: What is ovarian hyperstimulation syndrome (OHSS)?

If you need more information about PCOS, click here: Polycystic ovary syndrome (PCOS): causes, symptoms, and treatment.

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FAQs from users: 'What are the benefits of in vitro maturation of oocytes?', 'Is in vitro maturation a good option for women with PCOS?' and 'Is in vitro maturation of oocytes successful?'.

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Authors and contributors

 Elena Santiago Romero
Elena Santiago Romero
Bachelor's Degree in Medicine and Surgery from the Autonomous University of Madrid. Master's Degree in Human Reproduction from the King Juan Carlos University and the Valencian Infertility Institute (IVI). Several years of experience as a gynecologist specializing in Reproductive Medicine. More information about Elena Santiago Romero
License: 282864218
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV
Adapted into english by:
 Romina Packan
Romina Packan
inviTRA Staff
Editor and translator for the English and German edition of inviTRA. More information about Romina Packan

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