@article{Cheng2009,
author = {Cheng, D. and Schwarz, E.B. and Douglas, E. and Horon, I.},
title= {Unintended pregnancy and associated maternal preconception, prenatal and postpartum behaviors},
year = {2009},
doi = {10.1016/j.contraception.2008.09.009},
volume = {79},
number = {3},
pages = {194--198},
}