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2003 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.
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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 2003; 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.
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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.
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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 2003 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 2003. For example, if a clinic started
a total of 50 cycles in 2003 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 2003 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 19
fresh-embryo cycles using nondonor eggs among women aged 41–42 years. Of
these 19 cycles, 2—or 10%—were successful. However, because of the small
number of cycles, 10% is not a statistically reliable success rate, so
the success rate is presented as 2 / 19, meaning 2 out of 19.
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.
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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.
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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).
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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.
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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.
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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.
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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
(ASRM)* and the Society for
Assisted Reproductive Technology (SART)* have practice guidelines that address
this issue.
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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.
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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.
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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.
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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 39 and
40). |
- 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. For example, for cycles that used fresh embryos from
nondonor eggs, the percentage of cycles resulting in live births among
women younger than 35 was 37.4%, whereas the percentage of cycles
resulting in live births among women aged 38–40 was 20.6%.
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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 more information, see important factors to
consider when using the tables to assess a clinic.
See Appendix A for
a more detailed
explanation and examples of confidence intervals.
- Clinic
services
and profile
- Current name.
This name reflects name changes that may have occurred since 2003,
whereas the clinic name at the top of the table was the name of the
ART clinic as it existed in 2003. 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 2003. 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 regard-ing sharing of
donor eggs vary from clinic to clinic.
- Donor embryo.
These are embryos that were donated by another couple who previously
underwent ART treatment and had extra embryos available.
- Single women.
Clinics have varying policies regarding ART services for single
(unmarried) women.
- 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.
- 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.
- SART member.
In 2003, 377 of the 399 reporting clinics were SART members.
- Verified lab
accreditation. If “yes” appears next to this item, the ART clinic
uses an embryo laboratory accredited by one of the following
organizations:
- College of
American Pathologists (CAP)/American Society for Reproductive
Medicine (ASRM), Reproductive Laboratory Accreditation
Program.
- Joint Commission
on Accreditation of Healthcare Organizations (JCAHO).
- 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:
- CAP/ARSM, Reproductive
Laboratory Accreditation Program: For a list of accredited
laboratories, call 800-323-4040 and ask for Laboratory Accreditation.
- JCAHO: Call
630-792-5000 to inquire about the status of individual laboratories.
- 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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