[1] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Maternal & Child Hlth, CB 7445, Chapel Hill, NC 27599 USA
[2] RTI Int, Mil & Family Risk Behav Res Program, POB 12194, Res Triangle Pk, NC 27709 USA
[3] US Dept HHS, Family & Youth Serv Bur, Adm Children & Families, Switzer Bldg,330 C St SW,Room 3614, Washington, DC 20201 USA
[4] RTI Int, Ctr Hlth At Risk Populat, POB 12194, Res Triangle Pk, NC 27709 USA