For about 40% of ART procedures that used fresh nondonor eggs or embryos in 2005, standard IVF (in vitro fertilization) techniques were used: eggs and sperm were combined in the laboratory, the resulting embryos were cultured for 2 or more days, and one or more embryos were then transferred into the woman’s uterus through the cervix.

For most of the remaining ART procedures (60%), fertilization was accomplished using intracytoplasmic sperm injection (ICSI). This technique involves injecting a single sperm directly into an egg; the embryos are then cultured and transferred as in standard IVF.

For a small proportion of ART procedures, unfertilized eggs and sperm (gametes) or early embryos(zygotes) were transferred into the woman’s fallopian tubes. These procedures are known as gamete and zygote intrafallopian transfer (GIFT and ZIFT). Some women with tubal infertility are not suitable candidates for GIFT and ZIFT. GIFT and ZIFT are more invasive procedures than IVF because they involve inserting a laparoscope into a woman’s abdomen to transfer the embryos or gametes into the fallopian tubes. In contrast, IVF involves transferring embryos or gametes into a woman’s uterus through the cervix without surgery.

Figure 27: Types of ART Procedures Using Fresh Nondonor Eggs or Embryos, 2005.

Figure 28 shows the percentage of egg retrievals that resulted in a live birth for each type of ART procedure started in 2005. Success rates for the two predominant types of ART, IVF without ICSI and  IVF with ICSI, were similar. The success rates for cycles that used GIFT were much lower than for  cycles that used other ART procedures. See Figures 29–31 for further details on IVF procedures that used ICSI.
 

ICSI was developed to overcome problems with fertilization that sometimes occur in couples diagnosed with male factor infertility. In 2005, 58,079 ICSI cycles were performed. Approximately half of the ICSI cycles were performed for couples with a diagnosis of male factor infertility. However, diagnostic procedures may vary from one clinic to another, so the categorization of causes of infertility may also vary.

ICSI was developed to overcome problems with fertilization that sometimes occur among couples diagnosed with male factor infertility. In 2005, about 81% of couples diagnosed with male factor infertility used IVF with ICSI. Figure 30 presents the success rates for these ICSI procedures among couples diagnosed with male factor infertility. For comparison, these rates are presented alongside the success rates for ART cycles that used standard IVF without ICSI. This standard IVF comparison group includes couples with all diagnoses except male factor. Because ICSI can be performed only when at least one egg has been retrieved, the percentage of egg retrievals that resulted in live births are presented.

In every age group, success rates for the IVF with ICSI group were similar to the success rates for the groups that used standard IVF without ICSI. These results show that when ICSI was used for couples diagnosed with male factor infertility, their success rates were close to those achieved by couples who were not diagnosed with male factor infertility. Please note, however, that review of select clinical records revealed that reporting of infertility causes may be incomplete. Therefore, differences in success rates by causes of infertility should be interpreted with caution. (See Findings from Validation Visits for 2005 ART Data in Appendix A for additional information.)

What are the success rates for couples without a diagnosis of male factor infertility when ICSI is used?

As shown in Figure 29 , a large number of ICSI procedures are now performed even when couples are not diagnosed with male factor infertility. Figure 31 presents percentages of egg retrievals that resulted in live births for those cycles compared with ART cycles among couples who used IVF without ICSI. For every age group, the ICSI procedures were less successful. Please note, however, that review of select clinical records revealed that reporting of infertility causes may be incomplete. Therefore, differences in success rates by causes of infertility should be interpreted with caution. (See Findings from Validation Visits for 2005 ART Data in Appendix A for additional information.) Additionally, information was not available to completely determine whether this finding was directly related to the ICSI procedure or whether the patients who used ICSI were somehow different from those who use IVF alone. However, separate evaluation of various groups of patients with an  indication of being difficult to treat revealed a pattern of results consistent with those presented below. These difficult-to-treat groups included couples with previous failed ART cycles, couples diagnosed with diminished ovarian reserve, and couples with a low number of eggs retrieved (fewer than five). Within each of these groups, ART cycles that used IVF with ICSI had lower success rates compared with cycles that used IVF without ICSI.

Figure 31: Percentages of Retrievals That Resulted in Live Births Among Couples Not Diagnosed with Male Factor Infertility, by Use of ICSI and Woman’s Age, 2005.

Figure 32 shows that approximately 47% of ART cycles that used fresh nondonor eggs or embryos and progressed to the embryo transfer stage in 2005 involved the transfer of three or more embryos, about 18% of cycles involved the transfer of four or more, and approximately 6% of cycles involved the transfer of five or more embryos.

Figure 32: Number of Embryos Transferred During ART Cycles Using Fresh Nondonor Eggs or Embryos, 2005.

Figure 33 shows the relationship between the number of embryos transferred during an ART procedure in 2005 and the number of infants born alive as a result of that procedure. The success rate increased when two or more embryos were transferred; however, transferring multiple embryos also poses a risk of having a multiple-infant birth. Multiple-infant births cause concern because of the additional health risks they create for both mothers and infants. Also, pregnancies with multiple fetuses are potentially subject to multifetal reduction. Multifetal reduction can happen naturally (e.g., fetal death), or a woman or couple may decide to reduce the number of fetuses using a procedure called multifetal pregnancy reduction. Information on multifetal pregnancy reductions is incomplete and therefore is not provided here.

The relationships between number of embryos transferred, success rates, and multiple-infant births are complicated by several factors, such as the woman’s age and embryo quality. See Figure 34 for more details on women most at risk for multiple births.

Figure 33: Percentages of Transfers That Resulted in Live Births and Percentages of Multiple-Infant Live Births for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Number of Embryos Transferred, 2005.

Are success rates affected by the number of embryos transferred for women who have more embryos available than they choose to transfer?

Although, in general, transferring more than one embryo tends to improve the chance for a successful ART procedure (see Figure 33), other factors are also important. Previous research suggests that the number of embryos fertilized and thus available for ART is just as, if not more, important in predicting success as the number of embryos transferred. Additionally, younger women tend to have both higher success rates and higher likelihood of multiple-infant births. Figure 34 shows the relationship between the number of embryos transferred, success rates, and multiple-infant births for a subset of 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.

For this group, the chance for a live birth using ART was about 43% when only one embryo was transferred. If one measures success as the percentage of transfers resulting in singleton live births, the highest likelihood of live birth was observed with only one embryo transferred.

The proportion of live births that were multiple-infant births was about 40% with two embryos and about 45% with three embryos. Transferring three or more embryos also created an additional risk for higher-order multiple births (i.e., triplets or more).

Figure 34: Percentages of Transfers That Resulted in Live Births and Percentages of Multiple-Infant Live Births for ART Cycles in Women Who Were Younger Than 35, Used Fresh Nondonor Eggs or Embryos, and Set Aside Extra Embryos for Future Use, by Number of Embryos Transferred, 2005.

How long after egg retrieval does embryo transfer occur?

Once an ART cycle has progressed from egg retrieval to fertilization, the embryo(s) can be transferred into the woman’s uterus in the subsequent 1 to 6 days. Figure 35 shows that in 2005 approximately 67% of embryo transfers occurred on day 3. Day 5 embryo transfers were the next most common, accounting for about 23% of ART procedures that progressed to the embryo transfer stage.

Figure 35: Day of Embryo Transfer Among ART Cycles Using Fresh Nondonor Eggs or Embryos, 2005.

In general, is an ART cycle more likely to be successful if embryos are transferred on day 5?

As shown in Figure 35, in the vast majority of ART procedures, embryos were transferred on day 3 (67%) or day 5 (23%). Figure 36 compares success rates for day 3 embryo transfers with those for day 5 embryo transfers. In all age groups, the success rates were higher for day 5 embryo transfers than for day 3 transfers. However, some cycles do not progress to the embryo transfer stage because of embryo arrest (interruption in embryo development) between day 3 and day 5. These cycles are not accounted for in the success rates for day 5 transfers. Therefore, differences in success rates for day 3 and day 5 transfers should be interpreted with caution.

Figure 36: Percentages of Day 3 and Day 5 Embryo Transfers (Using Fresh Nondonor Eggs or Embryos) That Resulted in Live Births, by Woman’s Age, 2005.

Does the number of embryos transferred differ for day 3 and day 5 embryo transfers?

Figure 37 shows the number of embryos transferred on day 3 and day 5. Overall, fewer embryos were transferred on day 5 than on day 3. Approximately 56% of day 3 embryo transfers and 22% of day 5 embryo transfers involved the transfer of three or more embryos. The decrease in the number of embryos transferred on day 5, however, did not translate into a lower risk for multiple-infant births. See Figure 38 for more details on the relationship between multiple-infant birth risk and day of embryo transfer.

Figure 37: Number of Embryos Transferred During ART Cycles Using Fresh Nondonor Eggs or Embryos for Day 3 and Day 5 Embryo Transfers, 2005.