In Natural cycle IVF, the egg you naturally release during your monthly cycle is collected and fertilized with the sperm under controlled conditions of the IVF laboratory. Fertility drugs or hormone injections are not used in natural IVF.
The world’s first IVF baby—Louise Brown—was conceived with natural IVF but due to the lower success rates and higher number of abandoned cycles, the natural cycle treatment is hardly followed these days.
Natural IVF success rates
The success rates of natural IVF are not very encouraging. At around 8.8 percent success, as reported in a study by Assisted Conception Unit of King’s College School of Medicine and Dentistry (between 1993 and 1996), natural IVF is not considered an option by most doctors, which is why more recent success rates are not available.
However, there a few cases of natural IVF success, wherein women who failed to conceive with the usual IVF procedure, got positive results on trying natural IVF later.
How does natural cycle IVF work?
Natural IVF is a delicate treatment process, which must be performed with great precision and care. The process is similar to conventional IVF but it is less time-consuming and less invasive because no drugs are administered.
You will be tested first to check for your natural ovulation and if you are still ovulating, there should be no problem.
The rest of the steps in natural IVF are as follows:
- Visit the clinic on day 1 of your period and schedule your scans
- You might have to visit the clinic for scan every other day until around day 12, when egg pick up will be done under anesthesia
- The same day, that egg will be fertilized with sperm from your partner, and the resultant embryo will be kept in the lab for growth
- On day 3 – day 5, the embryo transfer will be done
However, the egg retrieval rate, embryo transfer rate, and the final success rates of natural IVF are all way too low, and most doctors recommend mild IVF over natural IVF.
Below are the noted advantages and disadvantages of natural IVF:
Advantages of natural IVF
- More patient friendly and safer – No hormones are administered to suppress your natural cycle and then to increase the number of eggs. You do not have to make multiple trips for dug injections and there is no risk of ovarian hyper stimulation syndrome (OHSS)— when too many eggs develop in the ovaries, making them large and painful—or the nausea and uneasiness that some women face with IVF drugs.
- Less expensive – IVF is expensive and almost about half of its cost can be attributed to the expensive drugs. However, with natural cycle IVF you only have to pay for the doctor’s fee and the lab charges.
- Good for older women – Women in their 40s or those with low ovarian reserves do not respond very well to IVF drugs, and even after taking all those injections, the doctor is able to collect only 2-3 eggs. So, they might want to take a chance with just one egg as collected in a natural cycle IVF.
- Can be repeated sooner – Due to the effect of stimulation drugs on the body, patients of conventional IVF have to wait for 2-3 months before they can go for the next cycle of IVF. However, in natural cycle, you can repeat the treatment every consecutive month.
- AMH, FSH levels not considered – Irrespective of your AMH and FSH levels, natural cycle IVF can be performed.
Disadvantages of natural cycle IVF
Cycle cancellation is high because the doctor is not controlling your hormones and ovaries. Only about 50% of patients who start a natural cycle IVF are able to go upto the stage of embryo transfer.
- Low chances of success – Higher number of eggs and embryos means there are greater chances of success in stimulated IVF, but in natural cycle IVF success rates are dismal.
- Failed egg collection – In a number of natural cycles no egg is collected because spontaneous ovulation can occur anytime before the planned egg retrieval.
- Failure to fertilize the egg – Since there is only one egg, the failure of egg fertilization (which happens in about 10% cases) means cancellation of the cycle.
- No embryo selection possible – When the doctor has multiple embryos, he/she is able to choose the best quality ones to transfer to the womb. But in natural IVF, since we are relying on only one egg and one embryo, embryo selection is not possible and the chances of the entire cycle being wasted are much higher.
- More chances required for success – With around 8% average success rate, the chances of conceiving in a natural cycle are 1/5th as compared to a conceiving in a stimulated cycle.
This above chart is made on the data shared by Lister Fertility Clinic, which states that IVF success improves with number of eggs used (irrespective of age)
Is natural cycle IVF for me?
Given the shortcomings noted above, natural cycle IVF is recommended only if:
- You are prone to OHSS or cannot take fertility drugs because of any other reason
- You do not want extra eggs or embryos because of some personal beliefs
- Your ovarian reserve is so low that even after being stimulated multiple eggs are not collected
Even though Louise Brown was conceived with natural cycle IVF, it took over a hundred attempts over ten years to get that one success.
Mild IVF or modified natural IVF—that use lower doses of stimulation drugs—may bring the desired results in patients who cannot undergo the regular stimulated IVF for any reason.
Discuss the options with your doctor to know the best course of treatment in your case.
Have you undergone a natural cycle of IVF? Can you share your experience?
For more information and advice on natural cycle IVF, fill-out the form on this page or consult with one of our top fertility experts around the world.
Geeta Nargund, John Waterstone, J.Martin Bland, Zoe Philips, John Parsons, Stuart Campbell, Cumulative conception and live birth rates in natural (unstimulated) IVF cycles, Human Reproduction, Volume 16, Issue 2, February 2001, Pages 259–262, https://doi.org/10.1093/humrep/16.2.259