Benefits and challenges brought by improved results from in vitro fertilization.

Abstract In vitro fertilization (IVF), in which preimplantation-stage embryos are produced after ovarian stimulation and retrieval of preovulatory oocytes, now accounts for almost 2% of all births in Australia. For clinics performing in the top quartile of national results, the chance of a live birth for a woman under 35 years from one round of egg retrieval and IVF treatment is greater than 50%, albeit still with a greater than 20% risk of twins or higher order multiple pregnancy. Similar or better live birth rates are now obtainable with the elective transfer of a single embryo at the stage of blastocyst (5-6 days in culture), a policy that if adopted for younger women can reduce the risk of twins in a clinic to less than 15%. Current developments centre around improvements to embryo culture and the testing of embryos for chromosomal normality and other genetic and epigenetic variables before transfer, made possible by licences for embryo research protocols now being issued under the Commonwealth's Research Involving Human Embryos Act 2002.