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2005 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 on the opposite page.
Technical terms are defined in the Glossary of
Terms.
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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 2005; the percentage of cycles that
were unstimulated; and the percentage of cycles that used a gestational
carrier. (See Glossary of Terms in Appendix B
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 of Terms in Appendix B 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 2005 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 2005. For example, if a clinic started
a total of 50 cycles in 2005 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 2005 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, the percentage of
cycles resulting in pregnancies is usually higher than the
percentage of cycles resulting in live births.
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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, the
percentage of retrievals resulting in live births is usually
higher than the percentage of cycles resulting in live births.
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 6,).
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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, the percentage of transfers resulting in live
births 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 pregnancy 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 live-born infants 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 45 and
46). |
- 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 2005,
whereas the clinic name at the top of the table was the name of the
ART clinic as it existed in 2005. 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 2005. 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.
- 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 2005, 374 of the 422 reporting clinics were Society for Assisted
Reproductive Technology (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 (NYSTB).
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 Westat. “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 following accrediting organizations directly:
- 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
Page last reviewed: 12/12/07
Page last modified: 12/12/07
Content source: Division
of Reproductive Health,
National Center for Chronic Disease
Prevention and Health Promotion
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