title: Growing Up in New Zealand cohort alignment with all New Zealand births.
abstract: OBJECTIVE
  To compare the birth characteristics of the Growing Up in New Zealand cohort with those of all New Zealand (NZ) births over a similar time period, and to describe cohort alignment to current NZ births.
  
  
  METHODS
  The Growing Up in New Zealand longitudinal study recruited 6,846 children from before birth via their pregnant mothers who were residing in the greater Auckland and Waikato regions during 2009 and 2010. Data were collected from mothers antenatally and six weeks after their expected delivery date, and from routine perinatal health records. These data were compared to Ministry of Health data for all births in NZ between 2007 and 2010.
  
  
  RESULTS
  The proportion of males and singleton births were not statistically different to national births. Compared to national births fewer of the cohort children were born low birth weight (4.9% vs. 6.1%, p<0.0001) or preterm (6.4% vs. 7.4%, p=0.001) and the cohort was expected to be more ethnically diverse than national births.
  
  
  CONCLUSIONS
  Birth parameters for the cohort were generally closely aligned to all NZ births in 2007-2010. Some statistically significant differences reflected small absolute differences, attributable in some part to cohort recruitment requiring survival to six weeks post expected delivery.
  
  
  CONCLUSIONS
  The explicit documentation of the alignment of the cohort to national data provides assurance that the study is well placed to deliver findings that can inform policy development relevant to the diversity of the contemporary NZ child population.
authors.affiliation: Centre for Longitudinal Research - He Ara ki Mua, The University of Auckland, New Zealand; Growing Up in New Zealand, The University of Auckland, New Zealand.
authors.forename: Susan M B
authors.initials: SM
authors.lastname: Morton
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Ramke
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kinloch
authors.forename: Cameron C
authors.initials: CC
authors.lastname: Grant
authors.forename: Polly Atatoa
authors.initials: PA
authors.lastname: Carr
authors.forename: Heidi
authors.initials: H
authors.lastname: Leeson
authors.forename: Arier Chi Lun
authors.initials: AC
authors.lastname: Lee
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Robinson
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D008137:Longitudinal Studies; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D011159:Population Surveillance; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000208:ethnology*; D047928:Premature Birth / Q000453:epidemiology*
keywords: New Zealand; cohort studies; demography; longitudinal studies; policy