FROM MULTIPLES TO SINGLETONS: NATIONAL TRENDS IN ASSISTED REPRODUCTIVE TECHNOLOGY–ASSOCIATED BIRTHS, 2016–2019

OBJECTIVE To evaluate temporal trends in plurality among assisted reproductive technology (ART)–associated births in the United States. DESIGN Population-based retrospective analysis. MATERIALS AND METHODS Final U.S. natality data from the Centers for Disease Control and Prevention WONDER database were analyzed for years 2016–2019, when ART use was consistently reported on birth certificates. Births conceived using ART were identified using the birth certificate indicator “Assisted Reproductive Technology Used.” ART-associated births were stratified by plurality (singleton, twin, and triplet or higher-order births) and year. Descriptive trends were evaluated, and changes in the distribution of plurality among ART-associated births over time were assessed. RESULTS From 2016 to 2019, the total number of assisted reproductive technology (ART)–associated births increased nationally. Over the same period, the distribution of plurality among ART-associated births shifted substantially. Singleton births increased from 65.7% of ART-associated births in 2016 to 79.5% in 2019, while twin births declined from 32.6% to 19.3%, and triplet or higher-order births decreased from 1.8% to 1.2%. These changes reflect a consistent temporal shift toward singleton ART-associated pregnancies over the study period. CONCLUSIONS Among ART-associated births in the United States, there has been a marked shift toward singleton pregnancies from 2016 to 2019, accompanied by declining multiple gestations. These findings suggest evolving ART practice patterns and have important implications for perinatal outcomes and reproductive medicine counseling.