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 6,721 pregnancies that resulted from ART cycles
using frozen nondonor embryos, 68% were singleton pregnancies, 20% were
twins, and 3% were triplets or more. Nine 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 (23%).
In 2005, 5,275 pregnancies from ART cycles that used
frozen nondonor embryos resulted in live births. Part B of
Figure 43 shows that approximately
23% of these live births produced more than one infant (21% twins and 2%
triplets or more). 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, 2005.
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