1. Three decades of twin births in the United States, 1980-2009;Martin;NCHS Data Brief,2012
2. Is twin childbearing on the decline? Twin births in the United States, 2014-2018;Martin;NCHS Data Brief,2019
3. Births: final data for 2009;Martin;Natl Vital Rep,2011
4. Births: final data for 2018;Martin;Natl Vital Stat Rep,2019
5. Trends in the occurrence, determinants, and consequences of multiple births;Blondel;Semin Perinatol,2002