Medical Health Encyclopedia

Natural (Unstimulated) In Vitro Fertilization Cycles. An alternative to superovulation for some couples is natural IVF cycles. It allows multiple, consecutive cycles of treatment. Natural IVF is far less expensive than standard hyperstimulation methods and avoids their risks, including multiple births and ovarian hyperstimulation syndrome (OHS).

• The process involves ultrasound and hormonal monitoring starting five days before the estimated ovulation day.
• No superovulation agents are used, such as FSH and hMG. The doctor, however, may administer an injection of hCG to stimulate the LH surge.
• The egg retrieval timing is based on detecting LH surge.
• A single egg is retrieved. The procedure that follows is similar to other IVF cycles.

The basic disadvantage to this approach is that the eggs may be released before there is a chance for them to be harvested. Women report far lower stress levels with this approach, however, even though it requires more treatment cycles. In one 2001 study, the live-birth rate was 32%. Not all women are appropriate candidates, however. Women should have regular menstrual cycles and infertility of unknown cause or associated with problems in the fallopian tubes. Pregnancy rates are still very low in older women.

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Clomiphene. Another gentler alternative to superovulation is the use of clomiphene before IVF, which works slightly better than unstimulated IVF.