[1] Univ N Carolina, Dept Maternal & Child Hlth, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA
[2] Univ N Carolina, Carolina Populat Ctr, Chapel Hill, NC USA
[3] Univ N Carolina, Dept Maternal & Child Hlth, Chapel Hill, NC USA
[4] Univ N Carolina, Dept Epidemiol, Chapel Hill, NC USA
[5] Univ N Carolina, Dept Nutr, Chapel Hill, NC USA
[6] Univ N Carolina, Dept Biostat, Gillings Sch Global Publ Hlth, Chapel Hill, NC USA