Section 5: ART Trends 2000-2009

Figure 51 shows the number of ART cycles performed, live-birth deliveries, and infants born using ART from 2000 through 2009. The number of ART cycles performed in the United States has increased, from 99,629 cycles in 2000 to 146,244 in 2009. The number of live-birth deliveries in 2009 (45,870) was nearly two times higher than in 2000 (25,228). The number of infants born who were conceived using ART also increased between 2000 and 2009. In 2009, 60,190 infants were born, which was nearly two times higher than the 35,025 born in 2000. Because in some cases more than one infant is born during a live-birth delivery (e.g., twins), the total number of infants born is greater than the number of live-birth deliveries.

Intracytoplasmic sperm injection (ICSI) was originally developed to use in ART cycles to improve fertilization rates when severe male factor infertility was the indication for using ART. Today, this procedure is widely used even among couples without a diagnosis of male factor infertility.

Figure 52 shows the number of ART cycles performed using ICSI from 2000 through 2009. Overall, the number of ART cycles with ICSI procedures continued to increase for all fresh cycles. During the past 10 years, the number of fresh nondonor cycles performed with ICSI nearly doubled, from 35,148 in 2000 to 66,490 in 2009. The number of fresh donor cycles with ICSI more than doubled, from 3,467 to 7,871 over the same period.

The number of frozen cycles (with or without ICSI) also nearly doubled, from 13,312 in 2000 to 26,069 in 2009 for frozen nondonor cycles and more than doubled from 2,882 to 6,659 for frozen donor cycles over the same period.

Note that the information on use of ICSI is not consistently collected across clinics for ART cycles using frozen embryos; therefore, these cycles are presented together as one group.

Figure 53 presents percentages of transfers that resulted in live births for ART cycles with or without ICSI. Percentages of transfers that resulted in live births are presented rather than percentages of cycles that resulted in live births because this is the only way to directly compare cycles using fresh embryos with those using frozen embryos.

In general, with or without ICSI, fresh donor cycles had the highest success rates when compared with fresh nondonor cycles or frozen cycles. However, when comparing success rates within each type of ART cycle, the percentage of transfers that resulted in live births among cycles without ICSI remained slightly higher than cycles with ICSI from 2000–2009.

The percentage of transfers that resulted in live births for cycles using fresh donor embryos without ICSI increased from 45% in 2000 to 56% in 2009, while cycles using fresh donor embryos with ICSI increased from 41% to 55% over the same period. Similar to trends with cycles using fresh donor embryos, the percentage of transfers that resulted in live births for fresh nondonor cycles with ICSI increased from 30% in 2000 to 36% in 2009, which was generally lower than for the fresh nondonor cycles without ICSI (33% in 2000 to 37% in 2009).

Note that the information on use of ICSI is not consistently collected across clinics for ART cycles using frozen embryos; therefore, these cycles are presented together as one group.

Singleton live births are an important measure of success because they entail a much lower risk than multiple-infant births for adverse infant health outcomes, including prematurity, low birth weight, disability, and death. Figure 54 shows that the percentage of transfers that resulted in singleton live births increased over time for all ART cycles with or without ICSI.

Although the total number of nondonor cycles using ICSI increased over the past 10 years (see Figure 52), percentages of transfers that resulted in singleton live births from these cycles were not any higher than those without ICSI.

Overall, percentages of transfers that resulted in singleton live births were consistently higher for fresh donor cycles than for fresh nondonor cycles and frozen cycles. Fresh donor cycles without ICSI increased from 26% in 2000 to 35% in 2009; a similar increase was observed for fresh donor cycles with ICSI. Over the same period, the percentage of transfers that resulted in singleton live births increased from 21% to 26% for fresh nondonor cycles without ICSI and from 20% to 25% with ICSI.

Note that the information on use of ICSI is not consistently collected across clinics for ART cycles using frozen embryos; therefore, these cycles are presented together as one group.

Figure 55 presents percentages of transfers that resulted in live births, by the age of the woman, for ART cycles using fresh nondonor eggs or embryos.

From 2000 through 2009, the percentage of transfers that resulted in live births for women younger than age 35 increased 23%, from 38% in 2000 to 47% in 2009. Over the same period, the percentage of transfers that resulted in live births increased 15% (from 33% to 38%) for women aged 35–37 years, 16% (from 24% to 28%) for women aged 38–40, and 17% (from 14% to 17%) for women aged 41–42. Please note that percentages of transfers that resulted in live births were rounded to the nearest whole number, while percent changes were calculated with raw data.

Singleton live births are an important measure of success because they have a much lower risk than multiple-infant births for adverse infant health outcomes, including prematurity, low birth weight, disability, and death. Figure 56 presents percentages of transfers that resulted in singleton live births, by the age of the woman, for ART cycles using fresh nondonor eggs or embryos.

From 2000 through 2009, the percentage of transfers that resulted in singleton live births for women younger than 35 increased 31%, from 24% in 2000 to 31% in 2009. Over the same period, the percentage of transfers that resulted in singleton live births increased 27% (from 21% to 27%) for women aged 35–37, 23% (from 18% to 22%) for women aged 38–40, and 19% (from 12% to 14%) for women aged 41–42. Please note that percentages of transfers that resulted in singleton live births were rounded to the nearest whole number, while percent changes were calculated with raw data.

Figure 57 presents the trends for the number of embryos transferred in fresh nondonor cycles that progressed to the embryo transfer stage. From 2000 through 2009, cycles that involved the transfer of one embryo more than doubled, from 6% to 14%; cycles that involved the transfer of two embryos doubled, from 26% in 2000 to 52% in 2009. Cycles that involved the transfer of three embryos decreased from 35% in 2000 to 23% in 2009, and cycles that involved the transfer of four or more embryos decreased dramatically from 34% in 2000 to 12% in 2009.

As shown in Figure 57, the number of embryos transferred in fresh nondonor cycles has decreased during the past 10 years. Figure 58 shows the change over time in the number of embryos transferred for ART procedures in which the woman was younger than 35 and the couple chose to set aside some embryos for future cycles rather than transfer all available embryos at one time. Previous research suggests that the number of embryos available for an ART cycle is important in predicting success. Younger women also tend to have higher percentages of ART cycles that result in pregnancies and live births (see Figure 15).

Overall, the number of embryos transferred decreased among couples who chose to transfer fewer embryos than were available. In 2000, approximately 15% of ART cycles involved the transfer of four or more embryos; 40%, three embryos; and 45%, two embryos. By 2009, four or more embryos were transferred in about 1% of cycles, three in 8% of cycles, two in 77% of cycles, and one in 14% of cycles.

Figure 59 presents percentages of transfers that resulted in live births, by the number of embryos transferred for ART cycles using fresh nondonor eggs or embryos from 2000 through 2009. The percentage of transfers that resulted in live births increased for ART cycles that involved the transfer of one or two embryos (10% to 25% and 35% to 44%, respectively). However, over the same period, there were no increases for ART cycles that involved the transfer of three or four or more embryos (35% to 33% and 30% to 25%, respectively).

The relationship between the number of embryos transferred and success rates is complicated by several factors, such as the woman’s age and embryo quality. Trends over time may reflect changes in these factors.

Figure 60 shows changes over time in the number of embryos transferred and the percentage of transfers that resulted in live births for ART cycles in which the woman was younger than 35 and chose to set aside some embryos for future cycles rather than transfer all available embryos at one time. Previous research suggests that the number of embryos available for an ART cycle is an important predictor of success. Younger women also tend to have higher percentages of ART cycles that result in pregnancies and live births (see Figure 15).

For this group of women, the percentage of transfers that resulted in live births generally increased over time, regardless of the number of embryos transferred. The biggest increase was for cycles in which one embryo was transferred, from 30% in 2001 to 50% in 2009.

Percentages of transfers that resulted in live births for cycles involving the transfer of one embryo were comparable to those that involved two or three embryos. Elective single-embryo transfer minimizes the risk of multiple-fetus pregnancy and related adverse outcomes. In 2009, the Society for Assisted Reproductive Technology (SART) revised its embryo transfer guidelines to encourage single-embryo transfer among patients with good prognoses. (For more information, contact SART by telephone at 205-978-5000 or online at www.sart.org.)

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. Figure 61 shows percentages of multiple-infant live births for the four primary types of ART procedures.

For fresh nondonor cycles, the percentage of multiple-infant live births decreased 14% since 2000, from 35% of all live births in 2000 to 31% in 2009. Over the same period, the percentage of multipleinfant live births decreased 9% for frozen nondonor cycles, 17% for frozen donor cycles, and 6% for fresh donor cycles. Please note that percentages of cycles that resulted in multiple-infant live births were rounded to the nearest whole number, while percent changes were calculated with raw data.

Figure 62 presents percentages of multiple-infant live births by the age of the woman, for ART cycles using fresh nondonor eggs or embryos. From 2000 through 2009, the percentage of multiple-infant live births decreased 10% (from 39% to 35%) for women younger than 35, 18% (from 35% to 29%) for women aged 35–37, 16% (from 27% to 23%) for women aged 38–40, and 8% (from 18% to 16%) for women aged 41–42. Among women aged 43–44 and older than 44, the percentage of multiple-infant live births decreased considerably from 2008 to 2009 (26% and 20% respectively). Please note that percentages of multiple-infant live births were rounded to the nearest whole number, while percent changes were calculated with raw data.

Figure 63 presents the trends in percentages of transfers that resulted in live births and percentages of multiple-infant live births for ART cycles using fresh nondonor eggs or embryos. Overall, the percentage of transfers that resulted in live births increased from 32% in 2000 to approximately 37% in 2009. From 2000 through 2009, the percentage of singleton live births increased from 65% to 69%; the percentage of twin births remained stable, ranging from 29% to 32%; and the percentage of triplet-or-more births decreased considerably from 4% in 2000 to 2% in 2009.

It is important to note that twins, albeit to a lesser extent than triplets or more, are still at substantially greater risk of illness and death than singletons. These risks include low birth weight, preterm birth, and neurological impairments such as cerebral palsy. Both percentages of twin and triplet-or-more births remain significantly higher for ART births than for births resulting from natural conception.