NATURAL CYCLE (nIVF)
In nIVF, the naturally selected egg is recovered after a minimal medical intervention to be fertilized in the laboratory, and then transferred into the uterus after becoming an embryo. This method is more gentle than conventional treatment, because it excludes the stimulation of the ovaries using drugs.It eliminates the side effects of ovarian stimulation in addition to removing the risk of multiple pregnancies except monozygotic pregnancies (identical twins).
The risk of ovarian hyperstimulation syndrome is removed by the same lack of stimulation. Another benefit is the possibility of carrying out cycles in consecutive months.
Indications of nIVF
In general, nIVF is offered to patients with regular cycles, with normal ovarian reserve and less than 37 years old.
nIVF also appears to be a sensible alternative for certain populations of patients with a poor prognosis using ovarian stimulation.
nIVF is also an attractive alternative for women with a history of hormono-dependant cancer where you absolutely want to avoid ovarian stimulation.
The advantages of this minimally invasive treatment are undeniable and the method should be used more, often. However IVF with stimulation remains an essential tool for many infertile couples, especially when the woman is over 35 year-old.
Disadvantages of nIVF
The detractors of nIVF list the daily monitoring, the risk of premature ovulation, an increased risk of cycle cancellation, the requirement for staff to be available day and night, the risk of failing to obtain the oocyte and the chance of cancelling the embryo transfer as major negative points for nIVF. For those reasons, the proportion of cycles that reach embryo transfer from egg collection is around 50%. If there is an embryo transfer, a pregnancy will be obtained in 36% of cycles.
ICSI and embryo development
Image © Dr. J. Herrero Garcia, provided by EMD Serono, Canada