Assisted Reproductive Technology (ART) Surveillance
Excerpted from the latest (2010) ART report of Centers for Disease Control and Prevention (CDC), December 2013.
Since the first U.S. baby conceived with Assisted Reproductive Technology was born in 1981, both the use of advanced technologies to overcome infertility and the number of fertility clinics providing ART services have increased steadily in the United States. Overall, ART contributed to 1.5% of U.S. births in 2010.
ART includes fertility treatments in which both eggs and sperm are handled in the laboratory (i.e., In Vitro Fertilization and related procedures). ART does not include treatments in which only sperm are handled (i.e., intrauterine insemination) or procedures in which a woman takes drugs only to stimulate egg production without the intention of having eggs retrieved. Because an ART procedure consists of several steps, a procedure is often referred to as a cycle of treatment.
An ART cycle generally begins with drug-induced ovarian stimulation. If eggs are produced, the cycle progresses to the egg retrieval. After the eggs are retrieved, they are combined with sperm in the laboratory. If the eggs fertilize successfully, the most viable embryo(s) is/are selected for transfer by clinicians. If an embryo implants in the uterus, a clinical pregnancy is diagnosed by the presence of a gestational sac detectable by ultrasound. Most pregnancy losses occur within the first 12 weeks. Beyond 12 weeks of gestation, the pregnancy usually progresses to a live-birth delivery, which is defined as the delivery of one or more live-born infants.
ART procedures are classified into four types based on the source of the egg (patient or donor) and the status of the embryos (fresh or thawed). Both fresh and thawed embryos might result from either the patient’s eggs or from the donor’s eggs. ART procedures involving fresh embryos include an egg-retrieval stage. ART procedures that use thawed embryos do not include an egg retrieval because the eggs were fertilized during a previous procedure, and the resulting embryos were cryopreserved for future use.
In 2010, a total of 147,260 ART procedures performed in 443 U.S. fertility clinics were reported to CDC. These procedures resulted in 47,090 live-birth deliveries (31.9% of ART procedures) and 61,564 infants. The largest numbers of ART procedures were performed among residents of six states: California (18,524), New York (excluding New York City) (14,212), Illinois (10,110), Massachusetts (9,854), New Jersey (8,783), and Texas (8,754). These six states also had the highest number of live-birth deliveries as a result of ART procedures.
A substantial proportion (43.4%) of ART-conceived infants were twin conceptions, and a smaller proportion (3.0%) were triplets and higher order infants.
Nationally, among cycles in which donor eggs were not used, the average number of embryos transferred increased with the age of the woman: 2.0 among women aged less than 35 years, 2.4 among women aged 35 to 40 years, and 3.0 among women aged more than 40 years.
Elective single embryo transfer rates decreased with increasing age: 10.0% among women aged less than 35 years, 3.8% among women aged 35 to 40 years, and 0.6% among women aged more than 40 years.
Reducing the number of embryos transferred per ART procedure among all age groups and promotion of elective single-embryo transfer procedures, when clinically appropriate, is needed to reduce multiple births, including twin births. Improved patient education and counseling on the risks of twins might be useful in reducing multiple births since twins account for the majority of multiples.