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Section 2: ART Cycles Using Fresh, Nondonor Eggs or Embryos (Part A)

Section 2 it is broken up into three parts. Part A contains Figures 6–15.

What are the steps for an ART cycle using fresh nondonor eggs or embryos?

 

Figure 6 presents the steps for an ART cycle using fresh nondonor eggs or embryos and shows how ART users in 2011 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 (GIFT or ZIFT).

If one or more of the transferred embryos implant within the woman’s uterus, the cycle then may progress 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 canceled at any step for specific medical reasons (e.g., no eggs are produced, the embryo transfer was not successful) or by patient choice.

Figure 6: Outcomes of ART Cycles Using Fresh Nondonor Eggs or Embryos,
by Stage, 2011.

Download Slide 6 [PDF - 238KB]

Why are some ART cycles canceled?

In 2011, a total of 10,304 ART cycles (about 10% of all 101,213 cycles using fresh nondonor eggs or embryos) were canceled before the egg retrieval step (see Figure 6). Figure 7 shows reasons that the cycles were canceled. For approximately 83% of these cycles, there was no or inadequate egg production. Other reasons included a too-high response to ovarian stimulation medications (i.e., potential for ovarian hyperstimulation syndrome), concurrent illness, or patient withdrawal for other reasons.

Figure 7: Reasons ART Cycles Using Fresh Nondonor Eggs or Embryos Were Canceled, 2011.

Download Slide 7 [PDF - 239KB]

How are success rates of ART measured?

Figure 8 shows success rates using six different measures for ART cycles using fresh nondonor eggs or embryos in 2011, each providing slightly different information. The majority of success measures have increased slightly since CDC began monitoring them in 1995 (see Section 5).

  • Percentage of cycles that resulted in a pregnancy: This is higher than the percentage of cycles that resulted in a live birth because some pregnancies end in miscarriage, induced abortion, or stillbirth (see Figure 10).
  • Percentage of transfers that resulted in a pregnancy: This is higher than the percentage of cycles that resulted in a pregnancy because not all cycles proceed to transfer.
  • Percentage of cycles that resulted in a live birth (delivery of one or more live-born infants): This represents the average chance of having one or more live-born infants by using ART. This is referred to as the basic live birth rate in the Fertility Clinic Success Rate and Certification Act of 1992.
  • Percentage of transfers that resulted in a live birth: This is higher than the percentage of cycles that resulted in a live birth because not all cycles proceed to transfer.
  • Percentage of cycles that resulted in a singleton live birth: This is important because 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.
  • Percentage of transfers that resulted in a singleton live birth: This is higher than the percentage of cycles that resulted in a singleton live birth because not all cycles proceed to transfer.
Figure 8: Measures of Success for ART Cycles Using
Fresh Nondonor Eggs or Embryos, 2011.

Figure 8: Measures of Success for ART Cycles Using Fresh Nondonor Eggs or Embryos, 2011.

Download Slide 8 [PDF - 238KB]

What percentage of ART cycles result in a pregnancy?

Figure 9 shows the outcomes of ART cycles in 2011 that used fresh nondonor eggs or embryos. Most of these cycles (approximately 64%) did not produce a pregnancy; a very small proportion (less than 1%) resulted in an ectopic pregnancy (the embryo implanted outside the uterus), and about 36% resulted in clinical pregnancy. Clinical pregnancies can be further subdivided as follows:

  • 63% of clinical pregnancies resulted in a single-fetus pregnancy.
  • 30% resulted in a multiple-fetus pregnancy.
  • 7% ended before the number of fetuses could be accurately determined.

Figure 9: Outcomes of ART Cycles Using Fresh Nondonor Eggs or Embryos, 2011.

Download Slide 9 [PDF - 216KB]

Using ART, what percentage of pregnancies result in a live birth?

Figure 10 shows the outcomes of pregnancies resulting from ART cycles using fresh nondonor eggs or embryos in 2011. Approximately 82% of the pregnancies resulted in a live birth (58% in a singleton birth and about 23% in a multiple-infant birth). About 18% of pregnancies resulted in miscarriage, stillbirth, induced abortion, or maternal death prior to birth. For less than 1% of pregnancies, the outcome was unknown.

Although the birth of more than one infant 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 10: Outcomes of Pregnancies Resulting from ART Cycles Using Fresh Nondonor Eggs or Embryos, 2011.

Download Slide 10 [PDF - 239KB]

Using ART, what is the risk of having a multiple-fetus pregnancy or multiple-infant live birth?

Multiple-infant births are associated with greater health 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 11 shows that among the 36,266 pregnancies that resulted from ART cycles using fresh nondonor eggs or embryos in 2011, approximately 63% were singleton pregnancies and 30% were multiple-fetus pregnancies. Approximately 7% of pregnancies ended 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 (about 30%).

In 2011, a total of 6,462 pregnancies resulting from ART cycles ended in either miscarriage, stillbirth, induced abortion, or maternal death, and 206 pregnancy outcomes were not reported. The remaining 29,598 pregnancies resulted in live births. Part B of Figure 11 shows that about 29% of these live births resulted in more than one infant (28% twins and about 1% triplets or more). This compares with a multiple-infant birth rate of slightly more than 3% in the general U.S. population.

Although total percentages for multiples were similar for pregnancies and live births, there were more triplet or higher order pregnancies than births. Triplet or higher order pregnancies may be reduced to twins or singletons by the time of birth either naturally (e.g., fetal death), or if a woman and her doctor decide to reduce the number of fetuses using a procedure called multifetal pregnancy reduction. CDC does not collect information on multifetal pregnancy reductions.

Figure 11: Distribution of Multiple-Fetus Pregnancies and Multiple-Infant Live Births from ART Cycles Using Fresh Nondonor Eggs or Embryos, 2011.

Download Slide 11 [PDF - 264KB]

Using ART, what are the risks of having a preterm birth and low-birth-weight infant?

Preterm birth occurs when a woman gives birth before 37 full weeks of pregnancy. Low-birth-weight infants are born weighing less than 2,500 grams or 5 pounds, 9 ounces. Infants born preterm or with low birth weight are at greater risk of death in the first few days of life, as well as other adverse health outcomes, including visual and hearing impairments, intellectual and learning disabilities, and behavioral and emotional problems throughout life. Preterm births and low-birth-weight infants also cause substantial emotional and economic burdens for families.

Figure 12 shows percentages of preterm births and low-birth-weight infants resulting from ART cycles that used fresh nondonor eggs or embryos in 2011, by number of infants born. For singletons, it shows separately the percentage of preterm birth and low birth weight among infants born from pregnancies that started with one fetus (single-fetus pregnancies) and with more than one fetus (multiple-fetus pregnancies). Among singletons, the percentage of preterm births and low-birth-weight infants was higher for those from multiple-fetus pregnancies. In the general U.S. population, where singletons are almost always the result of a single-fetus pregnancy, 10% were born preterm and 8% had low birth weights in 2011 (most recent available data).

Taking the number of preterm births or low-birth-weight infants in the general population and comparing it with multiple‑fetus pregnancies resulting from ART is not meaningful because a substantial proportion of multiple-infant births are due to infertility treatments (both ART and non-ART). These data indicate that the risks of preterm birth and low birth weight are higher among infants conceived through ART than for infants in the general population. The increased risks are due, in large part, to the higher percentage of multiple-fetus pregnancies resulting from ART cycles.

Figure 12: Percentages of Births That Were Preterm or Low Birth Weight from ART Cycles
Using Fresh Nondonor Eggs or Embryos, by Number of Infants Born, 2011.

Figure 12: Percentages of Births That Were Preterm or Low Birth Weight from ART Cycles Using Fresh Nondonor Eggs or Embryos, by Number of Infants Born, 2011.

Download Slide 12 [PDF - 239KB]

What are the ages of women who use ART?

Figure 13 presents ART cycles using fresh nondonor eggs or embryos in 2011 according to the age of the woman who had the procedure. About 12% of these cycles were among women younger than age 30, almost 64% were among women aged 30–39, and approximately 24% were among women aged 40 or older. The mean age of women who had ART cycles using fresh nondonor eggs was slightly less than 36 and the median age was 36.

Figure 13: Age Distribution of Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2011.

Download Slide 13 [PDF - 239KB]

Do percentages of ART cycles that result in pregnancies, live births, and singleton live births differ among women of different ages?

A woman’s age is the most important factor affecting the chance of a live birth when her own eggs are used. Figure 14 shows percentages of pregnancies, live births, and singleton live births among women of different ages who had ART procedures using fresh nondonor eggs or embryos in 2011. Percentages of ART cycles resulting in live births and singleton live births are different because of the high percentage of multiple-infant deliveries counted among the total live births. The percentage of multiple-infant births is particularly high among women younger than age 35 (see Figure 28). Among women in their 20s, percentages of ART cycles resulting in pregnancies, live births, and singleton live births were relatively stable; however, percentages declined steadily among women in their mid-30s onward. For additional detail on percentages of ART cycles that resulted in pregnancies, live births, and singleton live births among women aged 40 or older, see Figure 15.

Figure 14: Percentages of ART Cycles Using Fresh Nondonor Eggs or Embryos That Resulted in Pregnancies, Live Births, and Singleton Live Births, by Age of Woman, 2011.

Download Slide 14 [PDF - 242KB]

How do percentages of ART cycles that result in pregnancies, live births, and singleton live births differ among women aged 40 or older?

Figure 15 shows percentages of pregnancies, live births, and singleton live births among women aged 40 or older who used fresh nondonor eggs or embryos in 2011. The percentage of ART cycles resulting in pregnancy was 25% among women age 40; the percentage of ART cycles resulting in live births for the women was about 17%, and the percentage of ART cycles resulting in singleton live births was 14%. All percentages dropped steadily with each 1-year increase in age. Among women older than age 44, percentages of live births and singleton live births were both about 1%. Women aged 40 or older generally have much higher percentages of live births using donor eggs (see Figure 39).

Figure 15: Percentages of ART Cycles Using Fresh Nondonor Eggs or Embryos That Resulted in Pregnancies, Live Births, and Singleton Live Births Among Women Aged 40 or Older, 2011.

Download Slide 15 [PDF - 239KB]

 

ART 2011 National Summary Presentation.
[PDF - 860KB]

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