Natural Cycle IVF
The first pregnancy resulting from IVF was obtained in a natural or unstimulated cycle. Over the years, with the advent of many excellent Gonadotropin hormones, the use of natural cycles in IVF management has lost its popularity. With time however, the risks associated with stimulated cycles such as OHSS, multiple gestations and high cost of cycle has made it clear that perhaps Natural cycle IVF or sometimes, minimal stimulation IVF cycle are a safe and viable option in certain group of women needing ART.
Typically, natural cycle IVF is offered to women who are “poor-responders” and have responded poorly in previous IVF stimulation cycle. These are women who show poor follicular recruitment and development despite the high dose or Gonadotropin administered. Most often poor responders are women above the age of 40yrs although it may occur in younger patients. These patients do poorly with any type of stimulation protocol and despite the high quantity of Gonadotropins administered. They also show lower quality oocytes and poor pregnancy rates.
Studies suggest that performing natural cycle IVF in these patients may be a valid alternative to egg donation and stimulated IVF cycle in terms of costs and outcome. The best outcomes are seen in women who are 35yrs old or under. Since the side – effects of drug usage is non-existent in natural cycle IVF, it is much easier to undergo repeated attempts as compared to stimulated cycle where the compliance for repeated attempts is poor due to side – effect of medications, cost and the stress.
The protocol of natural cycle IVF is easy to perform and requires minimal transvaginal ultrasound monitoring. Blood tests for estradiol can be avoided. When the dominant follicle has reached 18mm, a single dose of HCG 10,000iu IM is administered egg retrieval is done 34-36 hrs later under general anesthesia.
The difficulties in natural cycle IVF are the high percentage of failure to collect eggs from each cycle. This may be due to mistakes in the timing of retrieval, or rupture of follicles, premature LH surge or deficient follicular growth.
In conclusion, natural cycle IVF is a valid alternative to poor responders (to traditional IVF)
This is because the pregnancy rate in this group remains comparable to that obtained in similar patients who used traditional IVF as the treatment of choice. The advantage enjoyed by the group who chose natural IVF was lower cost, higher safety and a slightly higher implantation rates.
In women below the age of 40yrs, (35yrs or 50yrs) the remaining follicles in the ovaries, even though very low in number appeared to be still of good quality. Consequently in this group, each IVF cycle has the same chance of success on the previous and ensuing cycle. Hence upto 4 consecutive attempts may be suggested in these women prior to proceeding with egg donation.