Several years ago, a couple of centers reported that if a woman had an FSH level over 15, her success rate with in Vitro fertilization (IVF) was zero. Since then, most physicians held strongly to this belief when advising women as to their best options for having children. Over the ensuing years, throughout the world, many groups challenged this hypothesis, based on the belief that nature provides a mechanism for selecting good eggs that is over-ridden by the strong stimulation protocols used in conventional IVF.
The concept of “minimal” and natural cycle IVF has developed as a result of this work, and indeed, it has been shown that women with poor prognoses, like high FSH levels can conceive viable pregnancies.
Physiology of Ovulation
From fetal life to menopause, several follicles begin to mature over a period of 4-8 weeks. In the absence of rising FSH levels, these follicles die. When a woman reaches puberty and the cyclic release of FSH and LH begin, the single follicle most efficient at using FSH takes over and becomes the “dominant” follicle. The other follicles undergo a process of dying called atresia. IVF stimulation protocols use high doses of FSH to salvage these follicles destined to die.
That is why the majority of eggs obtained in an IVF cycle do not produce high quality embryos or viable babies. Still, for women who respond well to these drugs, conventional IVF still offers the best chance for success in a single attempt.
Furthermore, the frozen embryos that result from many of these cycles increase the efficiency of the process if pregnancy does not occur or the couple desires a sibling later on.
For women with elevated FSH levels, previously poor responses, and recurring poor embryo quality, the cost and side effects of high-dose protocols may not be worthwhile. While controversial, some physicians believe that these protocols may lower egg vitality or decrease uterine receptivity, making this approach even less desirable for these poor prognosis patients.
The keys to success with minimal or natural IVF are individualization of treatment and patience. Each woman’s situation must be considered separately in deciding what protocol to use. Patients and clinicians need to be patient and understand that there will be set-backs like failed egg retrievals and cancelled cycles.
However, since the emotional, physical, and financial costs of commencing these cycles is relatively low, it is easier for women to get back into treatment and try again quickly.
Natural Cycle IVF
As the name implies, natural cycle IVF uses no drugs to facilitate egg production. The cycles are not totally natural, because a single injection of hCG or Lupron is used to prepare the egg for retrieval. Occasionally an antagonist is used to prevent pre-mature ovulation.
Progesterone supplementation is still given after the egg retrieval. Candidates for natural cycle IVF include women with high FSH levels, because the addition of FSH usually does not affect ovaries already saturated with FSH, and women who make poor quality embryos with stimulation.
With minimal IVF, the oral medication and low doses of injectable hormones are used to obtain a small number of eggs and avoiding premature ovulation, while avoiding hyperstimulation. Examples of potential candidates would be women who do not produce larger numbers of eggs on higher doses and women with poor egg quality in prior cycles.
Other Benefits of Minimal and Natural IVF
Since small numbers of eggs are retrieved, most women can undergo these procedures with sedation only, thus reducing the cost and risk of anaesthesia. In addition, since the egg numbers are low, a thinner needle is used for retrievals, thus decreasing the incidence of post-procedure internal bleeding; a rare but finite complication of conventional IVF.
Over the years, the doctors at OIA have performed these procedures on selected patients. Until now, we have not offered this as a comprehensive program and have not singled out these patients in our SART report. While Minimal and Natural IVF represent options for selected patients, one should assume that the pregnancy rates will be low, compared to conventional IVF.
Lower pregnancy rates are expected, since fewer embryos are transferred, more retrieval failures are seen, and the patients themselves usually have a poor prognosis by conventional standards. Thus, we still believe that conventional IVF is the treatment of choice for women who can respond appropriately to stimulation.
The following women should consider Minimal or Natural IVF as an option:
- Any woman with FSH greater than 10 and previously poor responses to stimulation.
- Women over age 40 with FSH greater than 10.
- Poor responders, despite normal FSH levels.
- Women with repeated poor embryo quality.