Risk of multiple birth associated with in vitro fertilization using donor eggs.

Multiple birth, which is associated with adverse fetal, infant, and maternal outcomes, is increasingly related to the use of in vitro fertilization (IVF). Among women undergoing IVF who use their own eggs, greater maternal age is associated with decreased risk of multiple birth; using donor eggs from younger women may negate this age effect. Data from 6,936 IVF procedures performed in the United States in 1996-1997 on women aged 35-54 years who used donor eggs were analyzed to assess the effect of maternal age, number of embryos transferred, and cryopreservation of extra, nontransferred embryos (an indicator of higher embryo quality) on risk of multiple birth. Greater maternal age did not decrease multiple-birth risk. Rates of multiple birth were related to number of embryos transferred and whether extra embryos had been cryopreserved, and they were high compared with those of IVF patients the same age who had used their own eggs. Among women who had extra embryos cryopreserved, transferring more than two embryos increased multiple-birth risk, with no corresponding increase in the chance for a livebirth. These results highlight the need to consider the age of the donor and embryo quality when making embryo transfer decisions involving use of donor eggs.