Funding for this research was provided by:
National Institute of Child Health and Human Development (contract #s N01-HD-3-3360, N01-HD-4-3363, N01-HD-4-3362, N01-HD-4-3361, N01-HD-4-3364)
Article History
Received: 15 February 2018
Accepted: 12 January 2019
First Online: 29 January 2019
Compliance with ethical standards
:
: Katherine W. Dempster, Aiyi Liu, and Tonja R. Nansel declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.