by Tenebris

Created on: July 02, 2008   Last Updated: August 24, 2008

So much have we come to take assisted reproductive technologies (ARTs) for granted in our modern world, it can be easy to forget that Louise Brown, the world's very first test tube baby, has only just reached her 30th birthday. Her birth on July 25, 1978, opened up a new frontier of hope for infertile couples. By the new millennium, over one hundred children had been born with the assistance of ARTs. Today, those numbers have risen to over three million.

The core of all ARTs is to assist the sperm to reach and fertilise the egg. This goal may be accomplished in several different ways. At the simplest, egg or sperm or both are introduced or transferred directly into the fallopian tubes or the uterus. At the most sophisticated (at the time of writing), a sperm is injected directly into an egg that has been removed from the body, the resulting embryo is allowed to grow to eight cells, one of those cells is tested to ensure the absence of an unwanted (usually lethal) genetic trait, and the resulting genetically 'clean' embryo is implanted into the uterus and allowed to grow to term.

The basic unit of each ART is the cycle: one cycle being the complete hormonal regimen required to stimulate fertility during a single menstral cycle, as well as egg aspiration or any other invasive procedures required for that particular ART. Few indeed are the lucky couples who manage to achieve pregnancy during a single cycle, yet the individual chance of successful embryo implantation and subsequent birth drops with every cycle undertaken.

A natural cycle is one in which the woman ovulates normally, without hormonal manipulation. However, virtually all ARTs are normally used in conjunction with hormonally induced superovulation in the woman. Although superovulation greatly increases the chances of success, it also can have significant complications, from polycystic ovary syndrome to (rarely) ovarian cancer. Even where they are not life-threatening, these complications can further reduce fertility.

Among the oldest and most basic ARTs are GIFT and ZIFT, which stands for gamete intrafallopian transfer and zygote intrafallopian transfer respectively. With GIFT, one or more eggs are aspirated from the ovaries and transferred into the fallopian tubes, where sperm have also been injected. With ZIFT, the eggs are removed entirely, fertilised in vitro, and then the resulting embryo is introduced back into the fallopian tubes. Even though these technologies have an unacceptably high chance of

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