Navigating the complexities of an infertility diagnosis and determining the most suitable treatment plan can be an overwhelming experience. Your Reproductive Endocrinologist may have recommended in vitro fertilization (IVF), often chosen for its high success rates. After some research, you will learn that there are multiple nuances and approaches to how an IVF cycle is implemented.
At Reproductive Medicine Associates, we are dedicated to empowering our patients with the knowledge and expertise to decide which assisted reproductive technology is best for their specific diagnosis and personal needs. Natural IVF and stimulated IVF represent two distinct methodologies, each with its unique approach to the same goal: conceiving a healthy child. This article will explore their differences and provide recommendations for most patients.
What is Natural IVF?
Natural IVF or natural cycle IVF (NC-IVF) — not to be confused with mini-IVF, which involves smaller doses of fertility drugs — does not include fertility drugs. The natural cycle is monitored, and the single egg available for that month is retrieved and inseminated.
Pros of natural IVF
- Less bloating than during a stimulated IVF cycle, as only one follicle is grown
- No need for medications
Cons of natural IVF
- Lower success rates compared to stimulated IVF
- Chance of cancellation if ovulation occurs before egg retrieval (i.e., premature ovulation)
- Only one egg is retrieved per cycle
What is Stimulated IVF?
Stimulated IVF is what most people think of when they hear the term “IVF.” It involves the use of fertility medications to stimulate the ovaries and grow multiple follicles (which can each contain up to one egg) for retrieval.
A standard IVF procedure involves several steps, including ovarian stimulation, egg retrieval, fertilization in the lab, and fresh or frozen embryo transfer.
Some couples may also opt for genetic testing such as preimplantation genetic testing for aneuploidy (PGT-A), preimplantation genetic testing for monogenic/single gene defects (PGT-M), or preimplantation genetic testing for structural chromosomal rearrangements (PGT-SR). These genetic tests allow our embryologists to choose only embryos most likely to deliver a healthy baby.
According to research conducted by our fertility specialists at RMA, women with three chromosomally normal embryos from a stimulated IVF cycle have a 94.9% chance of achieving a successful pregnancy.
Who is a good candidate for stimulated IVF?
Good candidates for stimulated IVF include women who:
- Have not been successful with other fertility treatments, such as intrauterine insemination (IUI)
- Have certain conditions, including endometriosis, polycystic ovary syndrome (PCOS), or unexplained infertility
- Have damaged or blocked fallopian tubes
- Are at an advanced maternal age (35 or older)
- Have a partner with male factor infertility
- Have a history of recurrent pregnancy loss
Pros of stimulated IVF
- One of the most successful assisted reproductive technology (ART) approaches with higher success rates compared to natural IVF
- Gives individuals or couples the option to freeze extra embryos for future use
- Helps overcome underlying fertility issues, such as PCOS or endometriosis
Cons of stimulated IVF
- Fertility medications like follicle-stimulating hormone (FSH), human chorionic gonadotropin (hCG), gonadotropin-releasing hormone (GnRH) agonists and antagonists are typically used. These medications are expensive and sometimes have side effects.
- If multiple embryos are transferred, there is a higher risk of multiple pregnancies. RMA does not transfer more than one embryo. We exclusively perform Single Embryo Transfer for all patients.
Key Similarities Between Natural and Stimulated IVF
Both natural IVF and stimulated IVF involve monitoring with bloodwork and ultrasound, egg retrieval, fertilization, embryo development, possibility of preimplantation genetic testing, and embryo transfer.
In cases of male factor infertility, the process can also involve intracytoplasmic sperm injection (ICSI). This is when a single sperm is injected into an egg.
Key Differences Between Natural and Stimulated IVF
In natural IVF, there is no ovarian stimulation. Instead, fertility specialists rely on the woman’s natural brain signaling to grow a single follicle and retrieve the egg from that follicle.
In stimulated IVF, a combination of fertility medications helps stimulate the ovaries and promote the growth and maturation of multiple follicles (each containing one egg).
Here’s a quick breakdown of the most common types of hormonal medications used in stimulated IVF:
- Follicle-stimulating hormone (FSH) stimulates follicle growth. Examples of FSH include Gonal-F, Follistim, and Menopur.
- Human chorionic gonadotropin (hCG) can play multiple roles in the treatment. At low doses, it supports follicular growth. At high doses, it is used to “trigger” the final maturation of the eggs within the follicles and prepare for egg retrieval. Examples of trigger shot medications include Ovidrel (r-hCG), Pregnyl (u-hCG), and Novarel (u-hCG).
- Gonadotropin-releasing hormone (GnRH) agonists and antagonists bind to receptors in the brain to either stimulate or suppress the body’s natural production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Lupron is a GnRH agonist. Ganirelix, Cetrotide, and Fyremadel are GnRH antagonists. Provera (an oral progestin medication) can also be used to inhibit ovulation and works similarly to GnRH antagonists.
Success Rates and Risks Associated with Each Method
Every fertility clinic has unique IVF success rates, as reported by the Society for Assisted Reproductive Technology (SART). For this example, we will use success rates from our New Jersey practice. At this location, our stimulated IVF success rates for women under 35 (using their own eggs) have a live birth per new patient rate of 85.8% in 2020.
RMA’s Stance of Natural IVF Cycles
All of RMA’s fertility clinics exclusively perform stimulated IVF cycles for several reasons, including success rates, cost, and emotional considerations.
Success Rates
Ultimately, it boils down to success rates. Growing and retrieving multiple eggs during a cycle increases the likelihood that one of those eggs will develop into a healthy embryo. Plain and simple, stimulated, or traditional IVF cycles are significantly more successful.
Cost
While natural IVF cycles (without medication) appear to be less expensive at first glance, they are also less successful. Multiple treatments are needed to achieve success, and the cumulative cost can end up being much more expensive than a single stimulated IVF cycle.
Emotional Considerations
Every failed IVF cycle (whether natural or stimulated) is emotionally taxing. At RMA, we prioritize treatment paths that minimize time in treatment with the hope that the emotional, physical, and financial burdens of treatment can be minimized.
Future Family Planning
As women age, the chance of any single egg leading to a live birth decreases. If a stimulated IVF cycle is successful, sometimes additional embryos can be saved to be used for baby number two or three in the future. This is called fertility preservation.
Moreover, the ability to freeze extra embryos for future use is an advantage that can save time, money, and emotional energy in subsequent attempts, should the initial cycle not result in pregnancy.
Therefore, despite the more intensive nature of stimulated IVF, its benefits in terms of increased success rates and long-term emotional and financial considerations often make it the preferred choice for many individuals and couples seeking assisted reproductive technologies.
Takeaway
Making an informed decision about your fertility journey starts with understanding the different treatment options available to you.
Both natural and stimulated IVF offer a chance at achieving a successful pregnancy, but they differ in terms of the use of medications and success rate.
At RMA, we’re dedicated to providing our patients with personalized and comprehensive fertility treatment options.
Frequently Asked Questions
Success rates for natural IVF and stimulated IVF vary depending on individual factors such as age, fertility issues, and overall health.
In general, stimulated IVF often has higher success rates compared to natural IVF because it allows for the retrieval of multiple eggs, increasing the chances of a successful pregnancy. However, some studies show that older individuals with poor ovarian response may only have one available egg per month and, therefore, do no better with stimulated IVF than with natural IVF.
There are no legal age restrictions for IVF, but it’s important to note that success rates generally decrease with age, especially for women over 35.
At RMA, we recommend any woman interested in pursuing pregnancy with her own uterus schedule a consultation before her 50th birthday.
Mini IVF, or minimal stimulation IVF, uses low doses of medication to stimulate the ovaries. The goal is typically to produce more than one egg but less than the maximum number of eggs available in any one cycle. This option can be a good fit for individuals with lower egg reserves. Mini IVF is considered the middle ground between natural IVF and Stimulated IVF.
With so many IVF options available, figuring out the right approach can be overwhelming. It’s best to consult a fertility specialist who can assess your individual circumstances and medical history to determine the most appropriate IVF method for you.
