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2001 Assisted Reproductive Technology (ART) Report: Section 2, ART
Cycles Using Fresh, Nondonor Eggs or Embryos |
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This page contains
figures 3–13
Section 2A | Section
2B | Section 2C
What are the steps for an ART procedure using
fresh nondonor eggs or embryos?
Figure 3 presents the steps
for an ART cycle using fresh nondonor eggs or embryos and shows how
ART users in 2001 progressed through these stages toward pregnancy
and live birth.
An ART cycle is started when
a woman begins taking medication to stimulate the ovaries to develop
eggs or, if no drugs are given, when the woman begins having her
ovaries monitored (using ultrasound or blood tests) for natural egg
production.
If eggs are produced, the cycle then
progresses to egg retrieval, a surgical procedure in which
eggs are collected from a woman’s ovaries.
Once retrieved, eggs are combined
with sperm in the laboratory. If fertilization is successful, one or
more of the resulting embryos are selected for transfer, most
often into a woman’s uterus through the cervix (IVF), but sometimes
into the fallopian tubes (e.g., GIFT
or ZIFT).
If one or more of the transferred
embryos implant within the woman’s uterus, the cycle then progresses
to clinical pregnancy.
Finally, the pregnancy may progress
to a live birth, the delivery of one or more live-born
infants. (The birth of twins, triplets, or more is counted as one
live birth.)
A cycle may be discontinued at any
step for specific medical reasons (e.g., no eggs are produced, the
embryo transfer was not successful) or by patient choice.
![Figure 3: Outcome of ART Cycles Using Fresh Nondonor Eggs or Embryos, by Stage, 2001.](sectionimage/figure3.jpg)
Figure
3: Outcome of ART Cycles Using Fresh Nondonor Eggs or Embryos, by
Stage, 2001.
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Why are some ART
cycles discontinued?
In 2001, 11,349 ART cycles (14%) were discontinued before
the egg retrieval step (see Figure 3).
Figure 4 shows reasons that the
cycles were stopped. For 84% of these cycles, there was no or inadequate
egg production. Other reasons included too high a response to ovarian
stimulation medications (i.e., potential for ovarian hyperstimulation
syndrome), concurrent medical illness, or a patient’s personal reasons.
![Figure 4: Reasons ART Cycles Using Fresh Nondonor Eggs or Embryos Were Discontinued in 2001.](sectionimage/figure4.jpg)
Figure
4: Reasons ART Cycles Using Fresh Nondonor Eggs or Embryos Were
Discontinued in 2001. |
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How is the
success of an ART procedure measured?
Figure 5 shows ART
success rates using six different measures, each providing slightly
different information about this complex process. All of these rates have
increased slightly each year since CDC began monitoring them in 1995 (see
Section 5).
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Pregnancy per cycle rate: the percentage of ART
cycles started that produced a pregnancy. This rate is higher than the
live birth per cycle rate because some pregnancies end in miscarriage,
induced abortion, or stillbirth (see
Figure 7).
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Live birth per cycle rate: the percentage of ART
cycles started that resulted in a live birth (a delivery of one or more
living babies). This rate is the one many people are most interested in
because it represents the average chances of having a live-born infant
by using ART.
Throughout this report, live birth rate means live birth
per cycle rate unless otherwise specified.
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Live birth per egg retrieval rate: the percentage
of ART cycles in which eggs were retrieved that resulted in a live
birth. It is generally higher than the live birth per cycle rate because
it excludes cycles that were canceled before eggs were retrieved. In
2001, 14% of all cycles using fresh nondonor eggs or embryos were
canceled for a variety of reasons (see
Figure 4).
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Live birth per transfer rate: includes only those
ART cycles in which an embryo or egg and sperm were transferred back to
the woman. This rate is the highest of these six measures of ART
success.
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Singleton live birth per cycle rate: the
percentage of ART cycles started that resulted in a singleton live
birth. Overall, singleton live births have a much lower risk than
multiple-infant births for adverse infant health outcomes, including
prematurity, low birth weight, disability, and death.
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Singleton live birth per transfer rate: the
percentage of ART cycles that resulted in a singleton live birth among
ART cycles in which an embryo or egg and sperm were transferred back to
the woman.
![Figure 5: Success Rates for ART Cycles Using Fresh, Nondonor Eggs or Embryos, by Different Measures, 2001.](sectionimage/figure5.jpg)
Figure
5: Success Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by
Different Measures, 2001.
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What percentage
of ART cycles results in a pregnancy?
Figure 6 shows the
results of ART cycles in 2001 that used fresh nondonor eggs or embryos.
Most of these cycles (66.5%) did not produce a pregnancy; a very small
proportion (0.7%) resulted in an ectopic pregnancy (the embryo implanted
outside the uterus), and 32.8% resulted in clinical pregnancy. Clinical
pregnancies can be further subdivided as follows:
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19.1% resulted in a single-fetus pregnancy.
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12.0% resulted in a multiple-fetus pregnancy.
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1.7% ended in miscarriage before the number of fetuses
could be accurately determined.
Figure
6: Results of ART Cycles Using Fresh Nondonor Eggs or Embryos, 2001.
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What
percentage of pregnancies results in live births?
Figure 7 shows the outcomes of
pregnancies resulting from ART cycles in 2001 (see
Figure 6). Slightly
more than 82% of the pregnancies resulted in a live birth (53% in
singleton births and 29% in multiple-infant births). Approximately 17% of
pregnancies resulted in an adverse outcome (miscarriage, induced abortion,
or stillbirth). For 0.8% of pregnancies, the outcome was not reported.
Although the birth of more than one baby is counted as one live birth,
multiple-infant births are
presented here as a separate category because they often are associated
with problems for both mothers and infants. Infant deaths and birth
defects are not included as adverse outcomes because the available
information for these outcomes is incomplete.
Figure
7: Outcomes of Pregnancies Resulting from ART Cycles Using Fresh Nondonor Eggs or Embryos, 2001. |
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Using
ART, what is the risk of having a multiple-fetus pregnancy or
multiple-infant birth?
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 8 shows that among the
26,550 pregnancies that resulted from ART cycles using fresh nondonor eggs
or embryos, 58% were singleton pregnancies, 29% were twin pregnancies, and
about 7% were triplet or greater pregnancies. About 5% of pregnancies
ended in miscarriage in which the number of fetuses could not be
accurately determined. Therefore, the percentage of pregnancies with more
than one fetus might have been higher than the 37% reported.
In 2001,
4,525 pregnancies resulting from ART cycles ended in either miscarriage,
stillbirth, or induced abortion, and 212 pregnancy outcomes were not
reported. The remaining 21,813 pregnancies resulted in live births. Part B
of Figure 8 shows that 36% of
these live births produced more than one infant (32.0% twins and 3.8%
triplets or more). This compares with a multiple-infant birth rate of 3% in
the general U.S. population.
Although
the total rates for multiples were similar between pregnancies and live
births, there were more triplet pregnancies than triplet 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. Information on medical multifetal
pregnancy reductions is incomplete and therefore is not provided here.
Figure
8: Risk of Having
Multiple-Fetus Pregnancy and Multiple-Infant Live Birth from ART Cycles
Using Fresh Nondonor Eggs or Embryos, 2001. |
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What
are the ages of women who have an ART procedure?
Figure 9 presents ART cycles
using fresh nondonor eggs or embryos according to the age of the woman who
had the procedure. About 69% of these cycles were among women aged 30–39.
Because very few women younger than age 22 used ART and very few women
older than age 46 used ART with their own eggs, those cycles are not
included in the figure.
Figure
9: Age Distribution of
Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2001. |
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Do
ART success rates differ among women of different ages?
A woman’s
age is the most important factor affecting the chances of a live birth
when her own eggs are used. Figure
10 shows the pregnancy rates, live birth rates, and singleton live
birth rates for women of different ages who had ART procedures using fresh
nondonor eggs or embryos in 2001. Live birth rates and singleton live
birth rates are different because of the high percentage of multiple-birth
deliveries counted among the total live births. The percentage of multiple
births is particularly high among younger women (see
Figures 8,
23, and 24).
Among women in their 20s, pregnancy rates, live birth rates, and singleton
live birth rates were relatively stable; however, success rates declined
steadily from the mid-30s onward as fertility declined with age. For
additional detail on success rates among women aged 40 years or older, see
Figure 11.
![Figure 10: Pregnancy Rates, Live Birth Rates, and Singleton Live Birth Rates for ART Cycles Using Fresh, Nondonor Eggs or Embryos, by Age of Woman, 2001.](sectionimage/figure10.jpg)
Figure
10: Pregnancy Rates, Live Birth Rates, and Singleton Live Birth Rates
for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Age of Woman,
2001. |
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How
do ART success rates differ for women who are 40 or older?
Success
rates decline with each year of age and are particularly low for women 40
or older. Figure 11 shows
pregnancy rates, live birth rates, and singleton live birth rates for
women 40 or older who used fresh nondonor eggs or embryos. The average
chance for pregnancy was about 23% for women aged 40; the live birth rate
for this age was about 16%, and the singleton live birth rate was 12%. All
rates dropped steadily with each 1-year increase in age. The live birth
rate for women aged 43 was approximately 6%, and the singleton live birth
rate for women aged 43 was 5%. The live birth rate for women older than 43
was 3%, and the singleton live birth rate was 2%. Women 40 or older
generally have much higher success rates using donor eggs (see
Figure 36).
![Figure 11: Pregnancy Rates, Live Birth Rates, and Singleton Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos Among Women Aged 40 and Older, 2001.](sectionimage/figure11.jpg)
Figure
11: Pregnancy Rates, Live Birth Rates, and Singleton Live Birth Rates
for ART Cycles Using Fresh Nondonor Eggs or Embryos Among Women Aged 40
and Older, 2001. |
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How do miscarriage
rates for ART patients vary among women of different ages?
A woman’s
age not only affects the chance for pregnancy when her own eggs are used,
but also affects her risk for miscarriage.
Figure 12 shows miscarriage
rates for women of different ages who became pregnant using ART procedures
in 2001. Miscarriage rates generally were near or below 14% among women
younger than 34. The rates began to increase among women in their
mid-to-late 30s and continued to increase with age, reaching 30% at age 40
and 41% at age 43.
The
miscarriage rates observed among women undergoing ART procedures using
fresh nondonor eggs or embryos appear to be similar to those reported in
various studies of other pregnant women in the United States.
![Figure 12: Miscarriage Rates Among Women Who Had ART Cycles Using Fresh, Nondonor Eggs or Embryos, by Age of Woman, 2001.](sectionimage/figure12.jpg)
Figure
12: Miscarriage Rates Among Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, by Age of Woman, 2001.
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How does
a woman’s age affect her chances of progressing through the various stages of
ART?
In 2001, a
total of 80,864 cycles using fresh nondonor eggs or embryos were started:
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35,984 in
women younger than 35
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17,791 in
women 35–37
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16,283 in
women 38–40
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7,044 in
women 41–42
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3,762 in
women older than 42
Figure 13 shows that a woman’s
chance of progressing from the beginning of ART to pregnancy and live
birth (using her own eggs) decreases at every stage of ART as her age
increases.
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As women
get older, the likelihood of a successful response to ovarian
stimulation and progression to egg retrieval decreases.
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As women
get older, cycles that have progressed to egg retrieval are slightly
less likely to reach transfer.
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The
percentage of cycles that progress from transfer to pregnancy also
decreases as women get older.
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As women
get older, cycles that have progressed to pregnancy are less likely to
result in a live birth because the risk for miscarriage is greater (see
Figure 12).
Overall,
35% of cycles started in 2001 among women younger than 35 resulted in live
births. This percentage decreased to 28% among women 35–37 years of age,
20% among women 38–40, 10% among women 41–42, and 4% among women older
than 42. As noted in Figures 10
and 11, the proportion of cycles
that resulted in singleton live births is even lower for each age group.
![Figure 13: Outcomes of ART Cycles Using Fresh Nondonor Eggs or Embryos, by Stage and Age Group, 2001.](sectionimage/figure13.jpg)
Figure
13: Outcomes of
ART Cycles Using Fresh Nondonor Eggs or Embryos, by Stage and Age Group, 2001.
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Section
1 | Section 2 |
Section
3 | Section 4 |
Section
5
Previous ART Reports
Implementation of the Fertility
Clinic Success Rate and Certification Act of 1992
Assisted Reproductive Technology: Embryo
Laboratory
Date last reviewed:
03/27/2006
Content source: Division
of Reproductive Health,
National Center for Chronic Disease
Prevention and Health Promotion
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