Problem/condition: In 1996, CDC initiated data collection regarding assisted reproductive technology (ART) procedures performed in the United States to determine medical center-specific pregnancy success rates, as mandated by the Fertility Clinic Success Rate and Certification Act (FCSRCA) (Public Law 102-493, October 24, 1992). ART includes fertility treatments in which both eggs and sperm are handled in the laboratory (i.e., in vitro fertilization and related procedures). Patients who undergo ART treatments are more likely to deliver multiple-birth infants than women who conceive naturally. Multiple births are associated with increased risk for mothers and infants (e.g., pregnancy complications, premature delivery, low-birthweight infants, and long-term disability among infants).
Reporting period covered: 2000.
Description of system: CDC contracts with a professional society, the Society for Assisted Reproductive Technology (SART), to obtain data from fertility medical centers located in the United States. Since 1997, CDC has compiled data related to ART procedures. The Assisted Reproductive Technology Surveillance System was initiated by CDC in collaboration with the American Society for Reproductive Medicine, the Society for Assisted Reproductive Technology, and RESOLVE: The National Infertility Association.
Results: In 2000, a total of 25,228 live-birth deliveries and 35,025 infants resulting from 99,629 ART procedures were reported to CDC from 383 medical centers that performed ART in the United States and U.S. territories. Nationally, 75,516 (76%) of ART treatments were freshly fertilized embryos using the patient's eggs; 13,312 (13%) were thawed embryos using the patient's eggs; 7,919 (8%) were freshly fertilized embryos from donor eggs; and 2,882 (3%) were thawed embryos from donor eggs. The national live-birth delivery per transfer rate was 30.8%. The five states that reported the highest number of ART procedures were California (13,194), New York (11,239), Massachusetts (8,041), Illinois (7,323), and New Jersey (5,506). These five states also reported the highest number of live-birth deliveries and infants born as a result of ART. Overall, 47% of women undergoing ART-transfer procedures using freshly fertilized embryos from their own eggs were aged <35 years; 23% were aged 35-37 years; 19% were aged 38-40 years; 7% were aged 41-42 years; and 4% were aged >42 years. Among ART treatments in which freshly fertilized embryos from the patient's eggs were used, substantial variation in patient age, infertility diagnoses, history of past infertility treatment, and past births was observed. Nationally, live-birth rates were highest for women aged <35 years (38%). The risk for a multiple-birth delivery was highest for women who underwent ART-transfer procedures using freshly fertilized embryos from either donor eggs (40%) or from their own eggs (35%). Among women who underwent ART-transfer procedures using freshly fertilized embryos from their own eggs, further variation by patient age and number of embryos transferred was observed. Of the 35,025 infants born, 44% were twins, and 9% were triplet and higher order multiples, for a total multiple-infant birth rate of 53%. Patient's residing in states with the highest number of live-birth deliveries also reported the highest number of infants born in multiple-birth deliveries.
Interpretation: Whether an ART procedure was successful (defined as resulting in a pregnancy and live-birth delivery) varied according to different patient and treatment factors. Patient factors included the age of the woman undergoing ART, whether she had previously given birth, whether she had previously undergone ART, and the infertility diagnosis of both the female and male partners. Treatment factors included whether eggs were from the patient or a woman serving as an egg donor, whether the embryos were freshly fertilized or previously frozen and thawed, how long the embryos were kept in culture, how many embryos were transferred, and whether various specialized treatment procedures were used in conjunction with ART. ART poses a major risk for multiple births. This risk varied according to the patient's age, the type of ART procedure performed, and the number of embryos transferred. In addition, the increased risk for multiple births has a notable population impact in certain states.
Public health actions: As use of ART and ART success rates continue to increase, ART-related multiple births are an increasingly important public health problem nationally and in many states. The proportion of infants born through ART in 2000 that were multiple births (53%) was substantially higher than in the general U.S. population during the same period. Data in this report indicate a need to reduce multiple births associated with ART. Efforts should be made to limit the number of embryos transferred for patients undergoing ART. In addition, continued research and surveillance is key to understanding the effect of ART on maternal and child health.