State-Specific Assisted Reproductive Technology Surveillance

Since the birth of the first US infant conceived with assisted reproductive technology (ART) in 1981, both the use of ART and the number of fertility clinics providing ART services have increased steadily.^1,2 ART includes fertility treatments in which eggs or embryos are handled in the laboratory (in vitro fertilization [IVF] and related procedures).¹ Although the majority of infants conceived through ART are singletons, women who undergo ART procedures are more likely than women who conceive without fertility treatments to have multiple births because multiple embryos may be transferred.³ Multiple births can pose increased risks for both mothers and infants, including obstetric complications, preterm birth, and low birth weight.^4–7

This data brief provides state-specific information on ART procedures performed in the United States in 2021. It compares ART birth outcomes with outcomes for all infants born in the United States in 2021. It includes data from the 50 states, the District of Columbia, and Puerto Rico.

Data for ART procedures and ART birth outcomes were obtained from the Centers for Disease Control and Prevention’s (CDC) National ART Surveillance System (NASS) for reporting years 2020 and 2021. See the Technical Notes at the end of this data brief for more information about NASS and the data collected through that system. Data for all infants born in the United States were obtained from CDC’s National Vital Statistics System for reporting year 2021.^8,9 To compare ART-conceived births in 2021 to all US births in 2021, ART-conceived births were aggregated from procedures performed in 2020 and 2021. The data are presented nationally and for the 50 States, the District of Columbia, and Puerto Rico and classified by mother’s reported state of residence at time of treatment.

This data brief presents data on all procedures initiated with the intent to transfer at least one embryo, including procedures that used thawed embryos for transfer. All cycles in which egg or embryo banking (freezing) was performed for future ART cycles were excluded.

The number and outcomes of ART procedures performed in 2021 were first calculated. ART procedures performed per million women 15-49 years of age are presented as a proxy measure of ART use. In previous years, ART procedures performed per million women aged 15-44 years were reported. This change was made given approximately 5% of ART users are older than 44 years; however, estimates from previous data briefs are not directly comparable. Data on the estimated size of the US female population were obtained from the US Census Bureau.¹⁰

The average number of embryos transferred and the proportion of embryo-transfer procedures performed with a single embryo in 2021 were calculated for women aged <35 years, 35–37 years, 38–40 years, and >40 years. The number of infants born in 2021 that were singletons, multiples (twins, triplets, and higher order), with low birth weight (<2,500g), or preterm (<37 weeks gestation) was calculated for ART-conceived infants and for all infants. Percentages were also calculated for each group. The proportion of ART-conceived infants among all infants with these outcomes was also calculated. The proportion of ART-conceived infants among all US births that had low birth weight, were preterm, or were small for gestational age (born at <10^th percentile of birth weight for gestational age) were calculated for singleton births.

In 2021, a total of 501 fertility clinics in the United States performed ART procedures and 453 (90.4%) provided data to CDC. States with the largest numbers of fertility clinics that provided data were California (78), New York (45), and Texas (43) (Table 1 and Figure 1).

In 2021, there were 246,087 ART procedures (range: 192 in Wyoming to 30,835 in California) performed at the 453 reporting US fertility clinics (Table 1 and Figure 2). These procedures resulted in 91,906 live-birth deliveries (range: 78 in Alaska to 12,389 in California) and 97,128 infants born (range: 82 in Alaska to 13,026 in California). Nationally, 3,250 ART procedures were performed per 1 million women aged 15–49 years (range: 751 in Puerto Rico to 8,515 in the District of Columbia) (Table 1 and Figure 3). ART use rates exceeded the national rate in the District of Columbia and the following 15 states: California, Connecticut, Delaware, Hawaii, Illinois, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Utah, Vermont, and Virginia. ART use exceeded 1.5 times the national rate in the District of Columbia and the following 7 states: Connecticut, Delaware, Illinois, Maryland, Massachusetts, New Jersey, and New York.

Nationally, among all ART transfer procedures, the average number of embryos transferred was similar across age groups (1.1 among women aged <35 years, 1.2 among women aged 35–37 years, 1.2 among women aged 38–40 years, and 1.3 among women aged >40 years) (Table 2). Single-embryo transfer (SET) rates among all embryo-transfer procedures were 85.8% among women aged <35 years (range: 27.5% in Puerto Rico to 95.9% in the District of Columbia) (Table 2 and Figure 4), 85.1% among women aged 35–37 years (range: 43.0% in Puerto Rico to 94.0% in the District of Columbia), 80.3% among women aged 38–40 years (range: 46.2% in Puerto Rico to 95.0% in Montana), and 76.8% among women aged >40 years (range: 37.0% in Puerto Rico to 86.8% in Mississippi).

In 2021, ART contributed to 2.3% of all infants born in the United States (range: 0.4% in Puerto Rico to 5.8% in the District of Columbia) (Table 3 and Figure 5). Approximately 87.5% of ART-conceived infants were singleton infants.  Approximately 12.5% of ART-conceived infants were multiples (range: 4.8% in the District of Columbia to 38.1% in Puerto Rico) (Table 4 and Figure 6). Approximately 12.1% of ART-conceived infants were twins, and approximately 0.4% were triplets and higher-order infants. Overall, ART contributed to 9.2% of all multiple births (range: 2.4% in Mississippi to 20.6% in Vermont) (Table 4 and Figure 7), 9.1% of all twin births, and 11.6% of all triplets and higher-order births (Table 4). Almost all (96.8%) of ART-conceived multiple births were twins. The percentage of multiple births was higher among infants conceived with ART (12.5%) (range: 4.8% in the District of Columbia to 38.1% in Puerto Rico) than among all infants born in the total US birth population (3.2%) (range: 2.3% in Puerto Rico to 3.8% in Connecticut).

Nationally, infants conceived with ART contributed to 3.8% of all low birth weight infants (range: 0.9% in Mississippi to 8.8% in Massachusetts) (Table 5). Among ART-conceived infants, 14.7% were low birth weight compared with 8.5% among all infants. ART-conceived infants contributed to 4.4% of all preterm infants (range: 1.3% in Alabama to 9.8% in Massachusetts) (Table 6 and Figure 8). The percentage of preterm births was higher among infants conceived with ART (19.7%) than among all infants born in the total US birth population (10.5%).

The percentage of low birth weight among singletons was 8.8% among ART-conceived infants and 6.9% among all infants born (Table 7). The percentage of preterm births among ART-conceived singleton infants was 13.2% compared with 8.8% among all singleton infants. The percentages of small for gestational age infants were 8.1% among ART-conceived infants compared with 9.2% among all infants.

Although singleton infants accounted for the majority of ART-conceived infants, multiple births from ART varied substantially among states and nationally contributed to 9.2% of all twins, triplets, and higher-order infants born in the United States. Variations in SET rates among states (or territory) were noted, which might, in part, account for high multiple birth rates observed in some states (or territory).

Reducing the number of embryos transferred and increasing the use of single embryo transfer procedures, when clinically appropriate, can help reduce multiple births and related adverse health consequences for both mothers and infants.³ Risks to mothers from multiple-birth pregnancy include higher rates of caesarean delivery, gestational hypertension, and gestational diabetes.⁵ Infants from multiple births are at increased risk for numerous adverse sequelae such as preterm births, birth defects, and developmental disabilities.^4–7

Long-term follow-up of ART-conceived infants through integration of existing maternal and infant health surveillance systems and registries with data available from NASS might help researchers monitor adverse outcomes at the population level.¹¹

1. Centers for Disease Control and Prevention. 2020 Assisted Reproductive Technology Fertility Clinic and National Summary Report. Centers for Disease Control and Prevention, US Dept of Health and Human Services; 2022.
2. Sunderam S, Zhang Y, Jewett A, Mardovich S, Kissin DM. State-Specific Assisted Reproductive Technology Surveillance, United States: 2020 Data Brief. Centers for Disease Control and Prevention, US Dept of Health and Human Services; 2022.
3. Practice Committee of the American Society for Reproductive Medicine and Practice Committee of the Society for Assisted Reproductive Technology. Guidance on the limits to the number of embryos to transfer: a committee opinion. Fertil Steril. 2021;116(4):651­–654.
4. American College of Obstetricians and Gynecologists. Multifetal gestations: twin, triplet, and higher-order multifetal pregnancies. Practice Bulletin No. 231. Obstet Gynecol. 2021;137:e145–e162.
5. MacKay AP, Berg CJ, King JC, et al. Pregnancy-related mortality among women with multifetal pregnancies. Obstet Gynecol. 2006;107(3):563–568.
6. Di Tommaso M, Sisti G, Colombi I, et al. Influence of assisted reproductive technologies on maternal and neonatal outcomes in early preterm deliveries. J Gynecol Obstet Hum Reprod. 2019;48(10):845–848.
7. Dawson AL, Tinker SC, Jamieson DJ, et al. Twinning and major birth defects, National Birth Defects Prevention Study, 1997-2007. J Epidemiol Community Health. 2016;70(11):1114–1121.
8. Centers for Disease Control and Prevention. Vital Statistics Online Data Portal. Accessed February 7, 2023. https://www.cdc.gov/nchs/data_access/vitalstatsonline.htm
9. Osterman MJK, Hamilton BE, Martin JA, et al. Births: final data for 2020. Natl Vital Stat Rep. 2022;70(17).
10. US Census Bureau. State Population by Characteristics: 2010-2021. Accessed March 19, 2023. https://www.census.gov/programs-surveys/popest/technical-documentation/research/evaluation-estimates/2021-evaluation-estimates/2010s-state-detail.html
11. Mneimneh AS, Boulet SL, Sunderam S, et al. States Monitoring Assisted Reproductive Technology (SMART) Collaborative: data collection, linkage, dissemination, and use. J Womens Health. 2013;22:571–577.

In 1995, CDC began collecting data on assisted reproductive technology (ART) procedures performed in fertility clinics in the United States as mandated by the Fertility Clinic Success Rate and Certification Act of 1992 (Public Law 102–493 [October 24, 1992]). For more details about the law, see www.cdc.gov/art/nass/policy.html.

ART includes all fertility treatments in which either eggs or embryos are handled outside a woman’s body. In general, ART procedures involve surgically removing eggs from a woman’s ovaries, combining them with sperm in the laboratory, and returning them to a female patient or gestational carrier, or donating them to another patient. They do not include treatments in which only sperm are handled (such as intrauterine insemination) or procedures in which a woman takes drugs only to stimulate egg production without the intention of having eggs surgically retrieved. ART includes but is not limited to in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), zygote intrafallopian transfer (ZIFT), tubal embryo transfer, egg and embryo cryopreservation, egg and embryo donation, and gestational surrogacy.

CDC collects ART data through the National ART Surveillance System (NASS), a web-based data collection system developed by CDC (www.cdc.gov/art/nass/index.html). Data collected include patient demographics, medical history, and infertility diagnoses; clinical information about ART procedure type; and information regarding resultant pregnancies and births. The data file contains one record per ART procedure (cycle of treatment performed).

Data from 453 fertility clinics that provided and verified information about the outcomes of the ART cycles are reported here. During 2021, data from 48 clinics are not included here because they did not report their data as required. Given the estimated number of ART cycles performed in these nonreporting clinics, we estimate that NASS covered approximately 98% of ART cycles performed in the United States in 2021. For more information about nonreporting clinics, see www.cdc.gov/art/nass/index.html.

Beginning with 2020 data, ART procedures performed per million women 15-49 years of age are presented as a proxy measure of ART use. This change was made given approximately 5% of ART users are older than 44 years. In previous data briefs, ART use was measured as ART procedures performed per million women aged 15-44 years. Therefore, estimates from previous year data briefs are not directly comparable.

The Data Brief reports on the numbers and outcomes of ART procedures performed in 2021 (Tables 1 and 2 and Figures 2, 3, and 4). To compare ART-conceived births in 2021 to all US births in 2021, ART-conceived births were aggregated from procedures performed in 2020 and born in 2021 and from procedures performed in 2021 and born in 2021 (Tables 3, 4, 5, 6, and 7 and Figures 5, 6, 7, and 8).

This publication was developed and produced by the National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP) of the Centers for Disease Control and Prevention (CDC).

The State-Specific Assisted Reproductive Technology Surveillance, United States: 2021 Data Brief was a collaborative effort by staff members in CDC’s Division of Reproductive Health and NCCDPHP’s Office of the Director. We wish to acknowledge Kelly Morris for her assistance with this report and Brian Taitt for creating the maps.

Sunderam S, Zhang Y, Jewett A, Mardovich S, Kissin DM. State-Specific Assisted Reproductive Technology Surveillance, United States: 2021 Data Brief. Centers for Disease Control and Prevention, US Dept of Health and Human Services; 2023.