ICSI was developed to overcome problems with fertilization that sometimes occur in couples diagnosed with male factor infertility. In 2003, about 80% of couples diagnosed with male factor infertility used IVF with ICSI. Figure 25 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 live birth per retrieval rates 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.

Figure 25: Live Births per Retrieval for ART Cycles Using Fresh Nondonor Eggs or Embryos Among Couples Diagnosed with Male Factor Infertility Who Used IVF with ICSI in Comparison to IVF Without ICSI, by Woman's Age, 2003.

As shown in Figure 24, a large number of ICSI procedures are now performed even when
couples are not diagnosed with male factor infertility. Figure 26 presents success rates per
retrieval for those cycles compared with ART cycles among couples who used IVF without ICSI. For every age group, the ICSI procedures were less successful. 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 used 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 diagnosed 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 27 shows that approximately 56% of ART cycles that used fresh nondonor eggs or
embryos and progressed to the embryo transfer stage in 2003 involved the transfer of three or more embryos, about 24% of cycles involved the transfer of four or more, and approximately 8% of cycles involved the transfer of five or more embryos.

Figure 28 shows the relationship between the number of embryos transferred during an ART procedure in 2003 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 can be associated with the possibility of multifetal reduction. Multifetal reduction can happen naturally (e.g., fetal death), or a woman may decide to reduce the number of fetuses using a procedure called multifetal pregnancy reduction. Information on medical multifetal pregnancy reductions is incomplete and therefore not provided here.

The relationships between number of embryos transferred, success rates, and multiple-infant births are complicated by several factors, such as age and embryo quality. See Figure 29  for more details on women most at risk for multiple births.

Are live birth 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 28), 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 multiple-infant birth rates. Figure 29 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 40% when only one embryo was transferred. If one measures success as the singleton live birth rate, the highest rate was observed with one embryo transferred.

The proportion of live births that were multiple-infant births was about 40% with two embryos and slightly more than 46% with three embryos. Transferring three or more embryos also created an additional risk for higher-order multiple births (i.e., triplets or more).

Figure 29: Live Births per Transfer and Percentages of Multiple-Infant 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, 2003.

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 30 shows that in 2003 approximately 73% of embryo transfers occurred on day 3. Day 5 embryo transfers were the next most common, accounting for about 18% of ART procedures that progressed to the embryo transfer stage.

Figure 30: Day of Embryo Transfer Among ART Cycles Using Fresh Nondonor Eggs or Embryos, 2003.

As shown in Figure 30, in the vast majority of ART procedures, embryos were transferred
on day 3 (73%) or day 5 (18%). Figure 31 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, it should be noted that day 5 embryo transfers may not be the best treatment option for all patients undergoing ART because some embryos may not survive to day 5.

Figure 31: Live Births per Transfer for ART Cycles Using Fresh Nondonor Eggs or Embryos for Day 3 and Day 5 Embryo Transfers, by Woman's Age, 2003.

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

Figure 32 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 64% of day 3 embryo transfers and 27% 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 33 for more details on the relationship between multiple-infant birth risk and day of embryo transfer.

Figure 32: Number of Embryos Transferred During ART Cycles Using Fresh Nondonor Eggs or Embryos for Day 3 and Day 5 Embryo Transfers, 2003.

In general, how does the multiple-birth risk vary by the day of embryo transfer?

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.

Part A of Figure 33 shows that among the 17,681 live births that occurred following day 3 embryo transfer, 67% were singletons, 30% were twins, and about 3% were triplets or more. Thus, approximately 33% of these live births produced more than one infant.

In 2003, 5,705 live births occurred following day 5 embryo transfer. Part B of Figure 33 shows that approximately 38% of these live births produced more than one infant (36% twins and approximately 2% triplets or more).

As shown in Figure 32, fewer embryos were transferred on day 5 than on day 3. While the reduction in the number of embryos transferred on day 5 was associated with a decrease in triplet or more births, it also was associated with an increase in twin births. Thus, the risk of having a multiple-infant birth was higher for day 5 embryo transfers. Multiple-infant birth rates for both day 3 and day 5 embryo transfers are much higher overall than those found in the general U.S. population (about 3%).

Figure 33: Risk of Having Multiple-Infant Live Birth for ART Cycles Using Fresh Nondonor Eggs or Embryos for Day 3 and Day 5 Embryo Transfers, 2003.

What are the success rates for women who use gestational carriers?

In some cases a woman has trouble carrying a pregnancy. In such cases the couple may use ART with a gestational carrier, sometimes called a surrogate. A gestational carrier is a woman who agrees to carry the developing embryo for a couple with infertility problems (the intended parents). Gestational carriers were used in 0.7% of ART cycles using fresh nondonor embryos in 2003 (671 cycles). Figure 34 compares success rates per transfer for ART cycles that used a gestational carrier in 2003 with cycles that did not. In most age groups, success rates for ART cycles that used gestational carriers were higher than success rates for those cycles that did not.

Figure 34: Comparison of Live Births per Transfer Between Cycles That Used Gestational Carriers and Those That Did Not (Both Using Fresh Nondonor Embryos), by ART Patient's Age, 2003.
 

How is clinic size related to success rates?

The number of ART procedures carried out every year varies among fertility clinics in the United States. In 2003, success rates tended to be slightly higher among clinics that performed a large number of cycles. For Figure 35, clinics were divided equally into four groups (called quartiles) based on the size of the clinic as determined by the number of cycles it carried out. The percentage for each quartile represents the average success rate for clinics in that quartile. For the exact number of cycles and success rates at an individual clinic, refer to the clinic table section of this report.

Figure 35: Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Clinic Size, 2003.