A woman’s age not only affects the chance for pregnancy when her own eggs are used, but also affects her risk for miscarriage. Figure 16 shows the percentages of ART cycles started in 2005 that resulted in miscarriage for women of different ages. The percentages of ART cycles that resulted in miscarriage were below 13% among women younger than 33. The percentages of ART cycles that resulted in miscarriages began to increase among women in their mid— to late 30s and continued to  increase with age, reaching 27% at age 40 and 64% among women older than 43.

The risk for miscarriage observed among women undergoing ART procedures using fresh nondonor eggs or embryos appear to be similar to those reported in various studies of other pregnant women in the  United States.

Figure 16: Percentages of ART Cycles Using Fresh Nondonor Eggs or Embryos That Resulted in Miscarriage, by Age of Woman, 2005.

What is the risk for pregnancy loss at different times during pregnancy among women of different ages?

A woman’s risk for pregnancy loss (loss of an entire pregnancy, or all fetuses in a multiple-fetus pregnancy) is affected by the duration of her pregnancy and her age. Figure 17 shows that between 13% and 55% of clinically-detected pregnancies (clinical detection through ultrasound performed between 4 and 6 weeks after the day of embryo transfer) are lost at some later point during the pregnancy, depending on the woman’s age. Among women younger than 35, 13% of pregnancies were lost and 87% continued through week 24. In contrast, among women older than 42, 55% of pregnancies were lost and only 45% continued through week 24. In all age groups, most pregnancy losses occurred before week 14 (i.e., during the first trimester). The risk of pregnancy loss after 24 weeks was less than 1% for all age groups because most pregnancies that progress beyond week 24 lead to live births.

Figure 17: Percentages of Pregnancies That Continued Past a Given Gestational Week Among Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, by Age of Woman, 2005.

How does a woman's age affect her chances of progressing through the various stages of ART?

In 2005, a total of 97,442 cycles using fresh nondonor eggs or embryos were started:

• 41,302 in women younger than 35
• 22,624 in women 35—37
• 19,482 in women 38—40
• 8,997 in women 41—42
• 5,037 in women older than 42

Figure 18 shows that a womans chance of progressing from the beginning of ART to pregnancy and live birth (using her own eggs) decreases at every stage of ART as her age increases.

• As women get older, the likelihood of a successful response to ovarian stimulation and progression to egg retrieval decreases.

• As women get older, cycles that have progressed to egg retrieval are slightly less likely to reach transfer.

• The percentage of cycles that progress from transfer to pregnancy also decreases as women get older.

• As women get older, cycles that have progressed to pregnancy are less likely to result in a live birth because the risk for miscarriage is greater (see Figure 16).

Overall, 37% of cycles started in 2005 among women younger than 35 resulted in live births. This percentage decreased to 29% among women 35–37 years of age, 20% among women 38—40, 11% among women 41—42, and 4% among women older than 42. As noted in Figures 14 and 15, the proportion of cycles that resulted in singleton live births is even lower for each age group.
 

Figure 18: Outcomes of ART Cycles Using Fresh Nondonor Eggs or Embryos, by Stage and Age Group, 2005.

Figure 19 shows the infertility diagnoses reported among couples who had an ART procedure using fresh nondonor eggs or embryos in 2005. 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 also vary.

• 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 19: Diagnoses Among Couples Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2005.

Figure 20 shows the percentage of ART cycles that resulted in live births according to the causes of infertility. (See  Figure 19, or the Glossary in Appendix B for an explanation of the diagnoses.) Although the national average success rate was about 28% (see Figure 7) success rates varied somewhat depending on the couple’s 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 success rates above the national average. 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. Please note, however, that a 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.)

Figure 21 shows the number of previous births among women who had an ART procedure using fresh nondonor eggs or embryos in 2005. Most of these women (about 72%) had no previous births, although they may have had a pregnancy that resulted in a miscarriage or an induced abortion. About 21% of women using ART in 2005 reported one previous birth, and about 8% 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.

Figure 21: Number of Previous Births Among Women Who Had ART Cycles Using Fresh Nondonor Eggs or Embryos, 2005.

Figure 22 shows the relationship between the success of an ART cycle and the woman’s 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 22: Percentages of ART Cycles Using Fresh Nondonor Eggs or Embryos That Resulted in Live Births, by Woman’s Age and Number of Previous Live Births, 2005.

Figure 24 presents ART cycles that used fresh nondonor eggs or embryos in 2005 according to whether previous ART cycles had been performed. For about 43%, 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.