1. Declines in unintended pregnancy in the United States, 2008–2001;Finer;N Engl J Med,2016
2. Unintended pregnancy and associated maternal preconception, prenatal and postpartum behaviors;Cheng;Contraception,2009
3. Family planning as a cost-saving preventive health service;Cleland;N Engl J Med,2011
4. The consequences of unintended childbearing: a white paper [internet];Logan,2007
5. The best intentions: unintended pregnancy and the well-being of children and families / committee on unintended pregnancy, Institute of Medicine, National Academy of Sciences;Brown,1995