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2001 Assisted Reproductive
Technology (ART) Report: How to Read a Fertility Clinic Table |
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This section is provided
to help consumers understand the information presented in the fertility
clinic tables. The number before each heading refers to the number of the
corresponding section in the sample clinic table.
Technical terms are defined in the
Glossary in Appendix B.
- Type of ART
used
This section gives the breakdown of ART cycle types that each clinic
performed using fresh nondonor eggs or embryos (IVF, GIFT, ZIFT, or
combinations thereof). It also lists the percentage of procedures that
involved intracytoplasmic sperm injection (ICSI), which was not
performed by all clinics in 2001; the percentage of cycles that were
unstimulated; and the percentage of cycles that used a gestational
carrier. (See Glossary for definitions of IVF, GIFT, ZIFT, ICSI, and
gestational carrier.)
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ART
patient diagnosis
Consumers may want to know what percentage of a particular clinic’s
patients have the same diagnosis as they do. (See
Glossary for definitions of diagnoses.) In addition, patients’
diagnoses may affect a clinic’s success rates. However, the use of
these diagnostic categories may vary somewhat from clinic to clinic.
- Verification
To have success rates published in the annual report, a clinic’s
medical director must verify the accuracy of the tabulated success
rates. The name of the individual who verified the clinic’s data is
shown.
- Success
rates by type of cycle
Success rates are given for the three categories of cycles described in
4A–C below: cycles using fresh embryos from
nondonor eggs, cycles using frozen embryos
from nondonor eggs, and cycles using donor
eggs. The ART success rates shown were calculated based on data from
all ART cycle types (IVF, both with and without ICSI; GIFT; and ZIFT).
Data from these procedures were combined because there was little
difference in success rates when we examined each type of ART procedure
separately.
The success rates indicate the average chance of success for the given
procedure at the clinic in 2001 for each of four age groups. Success
rates are calculated as the percentage of cycles started, egg
retrievals, or embryo transfers that resulted in either pregnancies or
live births at the ART clinic in 2001. For example, if a clinic started
a total of 50 cycles in 2001 and these resulted in 15 live births, the
average success rate for cycles started at that clinic would be
15 (births) ÷ 50 (cycles) = 0.3 or 30%.
Thus, the success rate at that clinic in 2001 was 30%, meaning that 30%
of cycles started that year resulted in a live birth.
Success rate calculations are very unstable if they are based on a small
number of cycles. Therefore, when fewer than 20 cycles are reported in a
given category, the rates are shown as fractions rather than
percentages. For example, the sample clinic carried out only five
fresh-embryo cycles using nondonor eggs among women aged 41–42 years. Of
these five cycles, two—or 40%—were successful. However, because of the
small number of cycles, 40% is not a reliable success rate, so the
success rate is presented as 2 / 5, meaning two out of five.
4A.
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Cycles
using fresh embryos from nondonor eggs
This section includes IVF, ICSI, GIFT, and ZIFT cycles that used a
woman’s own eggs. Cycles that used frozen embryos or donor eggs or
embryos are not included here.
- Percentage
of cycles resulting in pregnancies
(Number of pregnancies divided by number of cycles started,
expressed as a percentage of cycles)
A stimulated cycle is started when a woman begins taking fertility
drugs; an unstimulated cycle is started when egg production begins
being monitored. The number of cycles that a clinic starts is not
the same as the number of patients that it treats because some
women start more than one cycle in a year. Because some
pregnancies end in a miscarriage, induced abortion, or stillbirth,
this rate is usually higher than the live birth rate.
- Percentage
of cycles resulting in live births
(Number of live births divided by number of cycles started,
expressed as a percentage of cycles)
This number represents the cycles that resulted in a live birth
out of all ART cycles started. One live birth may include one or
more children born alive; that is, a multiple-infant birth (e.g.,
twins, triplets) is counted as one live birth.
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Percentage of
retrievals resulting in live births
(Number of live births divided by number of egg retrieval
procedures, expressed as a percentage of retrievals)
This number represents the cycles that resulted in a live birth
out of all cycles in which an egg retrieval was performed. The
number of egg retrievals a clinic performs often is smaller than
the number of cycles started because some cycles are canceled
before the woman has an egg retrieved. As a result, this rate is
usually higher than the live births per cycle started rate. Cycles
are canceled for many reasons: eggs may not develop, the patient
may become ill, or the patient may choose to stop treatment (see
Figure 4).
- Percentage
of transfers resulting in live births
(Number of live births divided by number of embryo transfer
procedures, expressed as a percentage of transfers)
This number represents the cycles that resulted in a live birth
out of all cycles in which one or more embryos were transferred
into the woman’s uterus or, in the case of GIFT and ZIFT, egg and
sperm or embryos were transferred into the woman’s fallopian
tubes. A clinic may carry out more egg retrievals than embryo
transfers because not every retrieval results in egg fertilization
and embryo transfer. For this reason, live birth rates based on
transfers generally will be higher than those reported for egg
retrievals and for cycles started.
- Percentage
of transfers resulting in singleton live births
(Number of singleton live births divided by number of embryo
transfer procedures, expressed as a percentage of transfers)
This number represents the cycles that resulted in the birth of a
single infant out of all cycles in which one or more embryos were
transferred into the woman’s uterus or, in the case of GIFT and
ZIFT, egg and sperm or embryos were transferred into the woman’s
fallopian tubes. Singleton births have a much lower risk than
multiple-infant births for adverse infant health outcomes,
including prematurity, low birth weight, disability, and death.
- Percentage
of cancellations
(Number of cycles canceled divided by the total number of
cycles, expressed as a percentage of cycles)
This number refers to the cycles that were stopped before an egg
was retrieved. A cycle may be canceled if a woman’s ovaries do not
respond to fertility medications and thus do not produce a
sufficient number of follicles. Cycles also may be canceled
because of illness or other medical or personal reasons.
- Average
number of embryos transferred
(Average number of embryos per embryo transfer procedure)
The average
number of embryos transferred varies from clinic to clinic. The
American Society for Reproductive Medicine* and the Society for
Assisted Reproductive Technology* have practice guidelines that address
this issue.
- Percentage
of pregnancies with twins
(Number of pregnancies with two fetuses divided by the total
number of pregnancies, expressed as a percentage of pregnancies)
A pregnancy with two fetuses is counted as one pregnancy.
- Percentage
of pregnancies with triplets or more
(Number of pregnancies with three or more fetuses divided by the
total number of pregnancies, expressed as a percentage of
pregnancies)
Pregnancies with multiple fetuses can be associated with increased
risk for mothers and babies (e.g., higher rates of caesarean
section, prematurity, low birth weight, infant death) and the
possibility of multifetal reduction.
A pregnancy with three or more fetuses is counted as one
pregnancy.
- Percentage
of live births having multiple infants
(Number of deliveries resulting in a birth of more than one
infant divided by the number of live births, expressed as a
percentage of live births)
A delivery of one or more babies is counted as one live birth.
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4B. |
Cycles
using frozen embryos from nondonor eggs
Frozen (cryopreserved) embryo cycles are those in which
previously frozen embryos are thawed and then transferred. Because
frozen-embryo cycles use embryos formed from a previous stimulated
cycle, no stimulation or retrieval is involved. As a result, these
cycles usually are less expensive and less invasive than cycles using
fresh embryos. In addition, freezing some of the embryos from a
retrieval procedure may increase a woman’s overall chances of
having a child from a single retrieval. |
4C. |
Cycles
using donor eggs
Success rates are presented separately for cycles using fresh donor
eggs or embryos and those using frozen donor embryos. Older women,
women with premature ovarian failure (early menopause), women whose
ovaries have been removed, and women with a genetic concern about
using their own eggs may consider using eggs that are donated by a
young, healthy woman. Embryos donated by couples who previously had
ART also may be available. Many clinics provide services for donor egg
and embryo cycles. For these cycle types, results from women in all
age groups (including older than 42) are reported together because
previous data show that patient age does not affect success rates with
donor eggs (see
Figures 36 and
37). |
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Age of
woman
Because a woman’s fertility declines with age, clinics report lower
success rates for older women attempting to become pregnant with their
own eggs. For this reason, rates for women using nondonor eggs or
embryos are reported separately for women younger than age 35, for women
35–37, for women 38–40, and for women 41–42. Clinic-specific outcome
rates are not shown for women older than 42 who undergo ART using their
own eggs because the number of women in this age group at each clinic is
small; therefore, a calculation of the live birth rate in older age
groups may not be meaningful. Readers are encouraged to
review national outcomes for these age groups.
The sample clinic table illustrates the decline in ART success rates
among older women: 22.4% of cycles started in women younger than 35
resulted in live births, whereas only 14.8% of cycles started in women
aged 38–40 resulted in a live birth.
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Confidence
interval
The tables show a range, called the 95% confidence interval,
that conveys the reliability of a clinic’s demonstrated success rate.
This range is calculated only if 20 or more cycles are reported in an
age category. (When fewer than 20 cycles are reported in a given
category, success rates are shown as fractions rather than percentages;
see paragraph 4, Success Rates by Type of Cycle.) In
general, the more cycles that a clinic performs, the narrower the range.
A narrow range means we are more confident that a clinic would have a
similar success rate if it treated other similar groups of patients
under similar clinical conditions. On the other hand, a wide range tells
us that a clinic’s success rate is more likely to vary under similar
circumstances because we had less information (fewer cycles) on which to
base our estimates. Even though one clinic’s success rate may appear
higher than another’s based on the confidence intervals, these
confidence intervals are only one indication that the success rate may
be better. Other factors also must be considered when comparing
rates from two clinics. For example, some clinics see more than the
average number of patients with difficult infertility problems, whereas
others discourage patients with a low probability of success. For
further information, see
important factors to
consider when using the tables to assess a clinic.
A more detailed
explanation and examples of confidence intervals
is located
in Appendix A.
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Clinic
services
and profile
• Current name. This name reflects name changes that may have
occurred since 2001, whereas the clinic name at the top of the table was
the name of the ART clinic as it existed in 2001. Some clinics not only
have changed their names but have reorganized as well. Reorganization is
defined as a change in ownership or affiliation or a change in at least
two of the three key staff positions (practice director, medical
director, or laboratory director). In such cases, no current name will
be listed, but a statement will be included that the clinic has
undergone reorganization since 2001. Also, in such cases, no current
clinic services or profile will be listed.
• Donor egg program. Some clinics have programs for ART using donor
eggs. Donor eggs are eggs that have been retrieved from one woman (the
donor) and then transferred to another woman who is unable to conceive
with her own eggs (the recipient). Policies regarding sharing of donor
eggs vary from clinic to clinic.
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Donor embryo. These are embryos that were donated by another
couple who previously underwent ART treatment and had extra embryos
available.
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Single women. Clinics have varying policies regarding ART services
for single (unmarried) women.
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Gestational carriers. A gestational carrier is a woman who carries
a child for another woman; sometimes such women are referred to as
gestational surrogates. Policies regarding ART services using
gestational carriers vary from clinic to clinic. Some states do not
permit clinics to offer this service.
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Cryopreservation. This item refers to whether the clinic has a
program for freezing extra embryos that may be available from a
couple’s ART cycle.
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SART member. In 2001, 354 of the 384 reporting clinics were SART
members.
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Verified lab accreditation. If “yes” appears next to this item, the
ART clinic uses an embryo laboratory accredited by one of the
following organizations:
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College of American Pathologists (CAP), Reproductive Laboratory
Accreditation Program
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Joint Commission on Accreditation of Healthcare Organizations
(JCAHO)
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New
York State tissue bank program
If
“pending” appears here, it means that the clinic has submitted an
application for accreditation to one of the above organizations and has provided proof of such application to SART. "No” indicates that the
embryo laboratory has not been accredited by any of these three
organizations.
CDC provides this information as a public service. Please note that CDC
does not oversee any of these accreditation programs. They are all
nonfederal programs. To become certified, laboratories must have in
place systems and processes that comply with the accrediting
organization’s standards. Depending on the organization, standards may
include those for personnel, quality control and quality assurance,
specimen tracking, results reporting, and the performance of technical
procedures. Compliance with these standards is confirmed by
documentation provided by the laboratory and by on-site inspections. For
further information, consumers may contact the accrediting
organizations directly, as follows:
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CAP,
Reproductive Laboratory Accreditation Program: For a list of accredited
laboratories, call 800-323-4040 and ask for Laboratory Accreditation.
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JCAHO:
Call 630-792-5000 to inquire about the status of individual
laboratories.
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New York
State: Call 518-485-5341 to find out which laboratories are certified
under the tissue bank regulations.
Further
information on laboratory accreditation is provided in
Appendix C.
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Links to non-Federal organizations found at this site are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. The CDC is not responsible for the content of the individual organization Web pages found at these links. |
Previous ART Reports
Implementation of the Fertility
Clinic Success Rate and Certification Act of 1992
Assisted Reproductive Technology: Embryo
Laboratory
Date last reviewed:
03/23/2006
Content source: Division
of Reproductive Health,
National Center for Chronic Disease
Prevention and Health Promotion
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