A viable alternative to egg donation.

What is Mild IVF treatment?

Mild in vitro fertilisation (IVF), also known as mini IVF, is our advanced alternative to conventional IVF. It is a good treatment to explore if you are  under  45, have a  low or very Low Ovarian Reserve,  Endometriosis or other  similar reproductive obstacles,  and have been  told that you can no longer use your own eggs  in  traditional infertility treatments.

Turning to donor eggs can be a complex and difficult decision. Our Mild IVF provides a viable “last chance” to fall pregnant using your own  egg cells.  That’s because the NatuVitro treatment process uses fewer injections  and  hormone  doses, which results in better quality eggs. We freeze the blastocysts in order to implant them in your next cycle, which in turn means that your uterine lining is in a  healthier  state to accept implantation.  At NatuVitro, we are experienced in working with highly challenging cases  and have witnessed many  unexpected and joyous pregnancies.  Read our low ovarian reserve and natural pregnancy success stories here.

What makes our Mild IVF treatment better?

When it comes to low ovarian reserve IVF, many conventional fertility clinics take the view that the lower the ovarian reserve, the higher the stimulation. We disagree. At NatuVitro we believe that little to no stimulation creates higher quality eggs. What’s more, we transfer a frozen blastocyst (day-5 embryo), which significantly increases the success rate. Our view is supported by numerous studies**, publications and years of experience. Read more about our mild IVF success stories here.

**Source: 2015 Assisted Reproductive Technology National Summary Report, Centers for Disease Control and Prevention, American Society for Reproductive Medicine, and Society for Assisted Reproductive Technology, Figure 32, October 2017.

Less stimulation medication

Mild IVF eliminates the need for excessive amounts of artificial stimulation medication and the associated side effects it can have on your body, allowing your well-being and natural cycle to be at an optimal state.

Anaesthesia-free (optional) 

The minimally invasive and painless ovarian puncture does not require the use of  anaesthesia. We use gentle protocols and the thinnest of needles to make your retrieval experience as painless as possible.  The majority of our patients don’t require anaesthesia, however, your specific needs will be taken into consideration when working together with your doctor.

Designed for you

You are unique, as is your body. As a boutique fertility clinic, we focus our attention on one patient at a time.
This means that we personalise your treatment to your needs. A one-size-fits-all solution is simply not an option.

Our Spanish location

Any form of Low Ovarian Reserve IVF  with  frozen embryos has a  consistently  higher success rate than fresh  cycles.  Unlike the rest of Europe*,  Spain’s  legislation allows for unlimited blastocyst culture and embryo freezing, two essential elements for Mild IVF to work.
See the country comparison here.

What is a Low Ovarian Reserve?

Ovarian reserve refers to the number of eggs a woman has available at any given time. A Low Ovarian Reserve directly impacts a woman’s fertility. Ovarian reserve decreases with age, and while the process is slow and progressive, it is more evident from age 37 onwards.

Hormonal changes due to ovarian failure can also influence and change the pattern of the menstrual cycle and the ovulation and implantation window may no longer be synchronised. Over time, this can make conceiving a child naturally increasingly difficult.

Low Ovarian Reserve in young women, although less common, is not unheard of. It can affect women who have suffered ovarian failure prematurely or can be triggered by other causes such as Endometriosis, medical therapies, hereditary factors, surgery, chemotherapy, or other environmental or lifestyle factors.

That is not to say that with having a Low Ovarian Reserve, a natural pregnancy can’t be achieved. There are Low Ovarian Reserve treatment options available, such as Mild IVF (mini IVF) for Low Ovarian Reserve, among others.

Is Mild IVF treatment right for me?

  Yes. And we have the success rates to prove it. You can definitely benefit from Mild IVF treatment if you:

  • Are between 18 and 45 years old.
  • Are physically capable of carrying a baby.
  • Are experiencing severe fertility obstacles and would prefer to use your own eggs instead of egg donation. 
  • Have been diagnosed with Low Ovarian Reserve or show Low Ovarian Reserve Symptoms.
  • Have been diagnosed with Endometriosis. 
  • Haven’t enjoyed success with traditional fertility treatments. 
  • Have a hormonal disorder such as polycystic ovary syndrome (PCOS) and run a high risk of developing Ovarian Hyperstimulation Syndrome (OHSS). 
  • Are a cancer warrior or survivor. 

  *Talk to us to find out if you are a good candidate for Mild IVF or would like to learn more about the best fertility
treatment for low ovarian reserve, or to explore other possibilities.

How Mild IVF works

Naturally, your dedicated NatuVitro specialist will have an in-depth conversation with you that is
appropriate to your specific fertility needs.  But here is a simplified version of how Mild IVF works.




This multi-level phase includes a  thorough  review of your medical history, a personalised  mild stimulation plan, follow-up  and  precise  ultrasound monitoring.  It’s important to note that medication is  kept to a minimum, which means less associated  side effects  and greatly reduced costs.


Ovulation Control 

Using  highly accurate  ultrasound monitoring, coupled with our intimate knowledge of your menstrual cycle, our NatuVitro medical team knows  the precise moment that your  follicles  are  at a perfect state of maturation and ready to induce ovulation. (However, unlike traditional clinics that use Human Chorionic Gonadotropin  (HCG) which replaces the natural Luteinizing hormone  (LH) surge, NatuVitro only uses medication that induces the natural LH surge.) Your fertility expert will then retrieve your best eggs using an ovarian puncture, which is a painless process that makes the use of anaesthesia optional.


Semen  Processing 

Your partner’s semen is collected and prepared for the IVF procedure in the lab. If you are using donor sperm, this has already been prepared and frozen by the donor sperm bank.  We take safety and traceability  extremely  seriously. Our  IVF lab  is equipped with  one of the most sophisticated  double security systems (among others),  designed to eliminate  any handling errors.


Blastocysts  Creation

Using Intra Cytoplasmic Sperm Injection (ICSI), our highly skilled embryologist injects a single sperm using a micro-needle directly into the egg. Inside the protected environment of the EmbryoScope Flex Incubator ®, they develop into  a  blastocyst  (day-5 embryo).


Blastocysts  Freezing 

Your 100% unaltered blastocysts are  now  frozen (vitrified),  which is necessary to synchronize with the implantation window.  The vitrified blastocysts are safely stored until you are 100% ready for your transfer.


Endometrial Preparation  

Your endometrium is primed and prepared to make sure that your lining is in optimal condition to receive embryo transfer. We  may use either  the Natural-cycle or  the  Hormone-replacement therapy, guided by your preference.


Embryo Transfer   

Your  embryo is  gently deposited into  your uterus.  Guided by ultrasound, it is a  risk-free and painless  procedure that is carried out in the comfort of our tranquil transfer  room.  No anaesthesia is required.



15 days after transfer, we take a blood pregnancy test. You will also have a  follow-up appointment  where we check in to see how you are feeling physically and emotionally and talk about the next steps.

Country Comparison


The Embryo Protection Law only allows the fertilisation of as many eggs that will be transferred, which is a maximum of 3. No embryo freezing is permitted which makes this an unfavourable destination for any form of Low Ovarian Reserve IVF.


French guidelines prevent doctors from carrying out egg retrievals in patients with 3 follicles or less. However, the majority of patients with Low Ovarian Reserve will have less than 3 follicles.


Although there are fewer restrictions, Italy’s doctors are required to justify each case. To avoid unnecessary conflict and admin, the tendency is to limit the number of embryos created and frozen.


Spain’s combination of favourable laws allow unlimited blastocyst culture and embryo freezing which are an absolute requirement for satisfactory results in patients with Low Ovarian Reserve.

Treatment cost


Dedicated Patient Assistant
IVF Witness Security
Endometrium Preparation
1 single frozen blastocyst transfer
Pregnancy test at NatuVitro
8th Week monitoring at NatuVitro


Does not include:

Mandatory blood tests required by law

Total cost €2,800

For rare phenotypes, please contact us

Common Questions

Visit the FAQ page

Can I do a fresh embryo transfer in Mild IVF?

We wouldn’t recommend it. The chances of conceiving are much greater if you transfer the embryos in a deferred cycle. This is because the uterus has been altered by the stimulation medication and we prefer it to be in an optimal state. For higher implantation success, we recommend that the transfer is made in an unstimulated cycle.

How long does the Mild IVF process take?

It is important to note that Mild IVF is a long-term commitment of roughly 5 to 6 months. You will be stimulated and your eggs will be retrieved and stored until you have a sufficient supply, or until your natural reserve is depleted. Each stimulated cycle is based on your menstrual cycle and takes around 10 to 14 days. You can expect fewer injections, blood tests and scans than with conventional IVF treatments.

Is it possible to do the treatment without aneasthesia?

Yes. The procedure is performed by a highly-skilled and experienced doctor using very fine instruments. Given that there are fewer follicles to retrieve, the procedure is a matter of minutes. That said, the decision of how you would like to proceed is entirely up to you.

How long will it take for me to get pregnant?

Mild IVF is a long-term commitment of about 5 to 6 months. You are stimulated and your eggs are retrieved and banked until you have sufficient banked supply or until the waning reserve is depleted.

Treatment Options