What is the risk of having a multiple-fetus pregnancy or
multiple-infant live birth from an ART cycle using frozen nondonor
embryos?
Multiple-infant births are associated with greater
problems for both mothers and infants, including higher rates of
caesarean section, prematurity, low birth weight, and infant disability
or death.
Part A of Figure 43
shows that among the 7,401 pregnancies that resulted from ART cycles
using frozen nondonor embryos, 66% were singleton pregnancies, 21% were
twins, and 3% were triplets or more. Ten percent of pregnancies ended in
miscarriage before the number of fetuses could be accurately determined.
Therefore, the percentage of pregnancies with more than one fetus might
have been higher than what was reported (24%).
In 2006, 5,797 pregnancies from ART cycles that used
frozen nondonor embryos resulted in live births. Part B of Figure 43
shows that approximately 24% of these live births produced more than one
infant. This compares with a multiple-infant birth rate of slightly more
than 3% in the general U.S. population.
Although the total rates for multiples were similar for
pregnancies and live births, there were more triplet-or-more pregnancies
than births. Triplet-or-more pregnancies may be reduced to twins or
singletons by the time of birth. This can happen naturally (e.g., fetal
death), or a woman and her doctor may decide to reduce the number of
fetuses using a procedure called multifetal pregnancy reduction. CDC
does not collect information on multifetal pregnancy reductions.
Figure 43: Risks of Having
Multiple-Fetus Pregnancy and Multiple-Infant Live Birth from ART Cycles
Using Frozen Nondonor Embryos, 2006.
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