Assisted reproductive technologies and multiple gestations.
Since the first in vitro fertilization infant was born in England in 1978, the practice of assisted reproductive technology (ART) has steadily increased as the technology and success rates have improved. The incidence of multiple gestations has also increased, primarily owing to the practice of transferring multiple embryos during an ART cycle. Guidelines for infertility clinics have been outlined, along with strategies to limit the number of embryos transferred (depending on the age of the patient) to achieve a lower risk of multiple births. Since 1997, a decrease has occurred in the number of embryos transferred and the percentage of gestations with three or more fetuses, accompanied by a steady increase in the percentage of live births per cycle.