In vitro fertilization, or IVF, in which eggs and sperm are mixed in a lab dish, led to a record 61,740 babies in 2012. That is 2,000 more than the previous year and 1.5 percent of all births in the nation.
The report by the Society for Assisted Reproductive Technology also finds that more women are using one embryo at a time to avoid multiple births, which raise the risk of prematurity and other problems.
Only 4 per cent of women under 35 used single embryos in 2007, but that rose to 15 percent in 2012.