Centers for Disease Control and Prevention, National Vital Statistics Reports Volume 68, Number 13. Births: Final Data for 2018 - Martin, J A; Hamilton, B E; Osterman, M JK; Driscoll, A K
[Figure 1. Number and Rate of Triplet and Higher-Order Multiple Births: United States, 1980–2018]. Published November 27, 2019. Accessed August 1, 2023 at: