This page contains figures 3–13
Section 2A | Section 2B | Section 2C
 

What are the causes of infertility among couples who use ART?

Figure 14 shows the infertility diagnoses reported among couples who had an ART procedure using fresh nondonor eggs or embryos in 2002. Diagnoses range from one infertility factor in one partner to multiple factors in either one or both partners. However, diagnostic procedures may vary from one clinic to another, so the categorization may be inexact.

• Tubal factor means that the woman’s fallopian tubes are blocked or damaged, making it difficult for the egg to be fertilized or for an embryo to travel to the uterus.
  
  
• Ovulatory dysfunction means that the ovaries are not producing eggs normally. Such dysfunctions include polycystic ovary syndrome and multiple ovarian cysts.
  
  
• Diminished ovarian reserve means that the ability of the ovary to produce eggs is reduced. Reasons include congenital, medical, or surgical causes or advanced age.
  
  
• Endometriosis involves the presence of tissue similar to the uterine lining in abnormal locations. This condition can affect both fertilization of the egg and embryo implantation.
  
  
• Uterine factor means a structural or functional disorder of the uterus that results in reduced fertility.
  
  
• Male factor refers to a low sperm count or problems with sperm function that make it difficult for a sperm to fertilize an egg under normal conditions.
  
  
• Other causes of infertility include immunological problems, chromosomal abnormalities, cancer chemotherapy, and serious illnesses.
  
  
• Unexplained cause means that no cause of infertility was found in either the woman or the man.
  
  
• Multiple factors, female only, means that more than one female cause was diagnosed.
  
  
• Multiple factors, female and male, means that one or more female causes and male factor infertility were diagnosed.

Figure 14: Diagnoses Among Couples Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2002.

Does the cause of infertility affect the chances of success using ART?

Figure 15 shows the percentage of live births after an ART procedure according to the causes of infertility. (See Figure 14 or the Glossary in Appendix B for an explanation of the diagnoses.) Although the national average success rate was slightly more than 28%, success rates varied somewhat depending on diagnosis; however, the definitions of these diagnoses may vary from clinic to clinic. In general, couples diagnosed with tubal factor, ovulatory dysfunction, endometriosis, male factor, or unexplained infertility had above-average success rates. The lowest success rate was observed for those with diminished ovarian reserve. Additionally, couples with uterine factor,“other” causes, or multiple infertility factors had below-average success rates.

Figure 15: Live Birth Rates Among Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, by Diagnosis, 2002.

How many women who use ART have previously given birth?

Figure 16 shows the number of previous births among women who had an ART procedure using fresh nondonor eggs or embryos in 2002. Most of these women (73%) had no previous births, although they may have had a pregnancy that resulted in a miscarriage or an induced abortion. About 20% of women using ART in 2002 reported one previous birth, and 7% reported two or more previous births. However, we do not have information about how many of these were ART births and how many were not. These data nonetheless point out that women who have previously had children can still face infertility problems, including the infertility of a new partner.

Figure 16: Number of Previous Births Among Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2002.

Do women who have previously given birth have higher ART success rates?

Figure 17 shows the relationship between the success of an ART cycle and the history of previous births. Previous live-born infants were conceived naturally in some cases and through ART in others. In all age groups, women who had a previous live birth were more likely to have a successful ART procedure.

Figure 17: Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Woman's Age and Number of Previous Live Births, 2002.

Is there a difference in ART success rates between women with previous miscarriages and women who have never been pregnant?

In 2002, 62,638 ART cycles were performed among women who had not previously given birth (see Figure 16). However, about 26% of those cycles were reported by women with one or more previous pregnancies that had ended in miscarriage. We do not have information on whether the previous pregnancies were the result of ART or were conceived naturally. Figure 18 shows the relationship between the success of an ART cycle and the history of previous miscarriage. In all age groups women who had a previous miscarriage had live birth rates that were comparable to the live birth rates among women who had never been pregnant. Thus, a history of unsuccessful pregnancy does not appear to be associated with reduced chances for success during ART.

Figure 18: Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Woman's Age and History of Miscarriage, Among Women with No Previous Births, 2002.

How many current ART users have undergone previous ART cycles?

Figure 19  presents ART cycles that used fresh nondonor eggs or embryos in 2002 according to whether previous ART cycles had been performed. For about 45%, one or more previous cycles were reported. (This percentage includes previous cycles using either fresh or frozen embryos.) This finding illustrates that it is not uncommon for a couple to undergo multiple ART cycles. We do not have information on when previous cycles were performed, nor do we have information on the outcomes of those previous cycles.

Figure 19: Number of Previous ART Cycles Among Women Undergoing ART in 2002 with Fresh Nondonor Eggs or Embryos.

Are success rates different for women using ART for the first time and women who previously used ART but did not give birth?

Figure 20 shows the relationship between the success of ART cycles performed in 2002 using fresh nondonor eggs or embryos and a history of previous ART cycles among women with no previous births. In all age groups up to age 42, success rates were lower for women who had previously undergone an unsuccessful ART cycle.

Figure 20: Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Woman's Age and History of Previous ART Cycles, Among Women with No Previous Births, 2002.

What are the success rates for women who have had both previous ART and previous births?

Figure 21  shows the relationship between the success of ART cycles performed in 2002 using fresh nondonor eggs or embryos and a history of both previous ART cycles and previous births. We do not have information on whether the previous births were the result of ART or were conceived naturally. However, among women with previous births, there was no decline in success rates if they had undergone previous ART cycles.

Taken together,  Figures 20 and 21 show that having undergone previous ART cycles may be related to the success of the current ART cycle. However, it is important to consider the outcomes of previous cycles and whether the woman has given birth in the past.

Figure 21: Live Birth Rates for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Woman's Age and History of Previous ART Cycles, Among Women with One or More Previous Births, 2002.

How many embryos are transferred in an ART procedure?

Figure 22 shows that approximately 62% of ART cycles that used fresh nondonor eggs or embryos and progressed to the embryo transfer stage in 2002 involved the transfer of three or more embryos, about 28% of cycles involved the transfer of four or more, and approximately 10% of cycles involved the transfer of five or more embryos.

Figure 22: Number of Embryos Transferred During ART Cycles Using Fresh Nondonor Eggs or Embryos, 2002.

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

Figure 23 shows the relationship between the number of embryos transferred during an ART procedure in 2002 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 24 for more details on women most at risk for multiple births.

Figure 23: Live Births per Transfer and Percentages of Multiple-Infant Births for ART Cycles Using Fresh Nondonor Eggs or Embryos, by Number of Embryos Transferred, 2002.

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 23), 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 24 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 47% 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 47% with three embryos. Transferring three or more embryos also created an additional risk for higher-order multiple births (i.e., triplets or more).

Figure 24: 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, 2002.