Thousands of cycles of in vitro fertilization (IVF) are performed each year. In the US, multiple births occur after 39% of IVF cycles, whereas in Europe, the figure is 26%. Indeed, multiple births are a major factor in the costs attributable to IVF. Reducing the multiple birth rate may reduce the overall costs of IVF, and providing insurance coverage of IVF may contribute to lowering multiple birth rates. The use of IVF is likely to expand in response to increases in infertility and scientific advances.