[1] UNSW Sydney, Ctr Big Data Res Hlth, Sydney, NSW, Australia
[2] UNSW Sydney, Sch Clin Med, Natl Perinatal Epidemiol & Stat Unit, Sydney, NSW, Australia
[3] Univ North Carolina Chapel Hill, Gillings Sch Global Publ Hlth, Dept Maternal & Child Hlth, Chapel Hill, NC USA
[4] Univ North Carolina Chapel Hill, Injury Prevent Res Ctr, Chapel Hill, NC USA
[5] UNSW Sydney, Ctr Big Data Res Hlth, Level 2,AGSM G27, Sydney, NSW 2052, Australia