title: Using record linkage to investigate perinatal factors and neonatal thyroid-stimulating hormone.
abstract: OBJECTIVE
  Studies examining the relationship between maternal and infant thyroid parameters have shown conflicting results. Record linkage provides an opportunity to examine the association between maternal and infant thyroid-stimulating hormone (TSH) levels. Our aim was to demonstrate the feasibility of record linkage of newborn screening (NBS), laboratory and birth databases for research by investigating the association between maternal and newborn TSH levels.
  
  
  METHODS
  The records of 2802 women with first trimester serum TSH concentrations were linked with population-based birth data and NBS data containing infant TSH levels. Association between moderately high neonatal TSH levels (>5 mIU/L) and maternal and infant characteristics was evaluated. The correlation and association between maternal and infant TSH levels were assessed using Pearson's correlation coefficient and multivariable linear regression, respectively.
  
  
  RESULTS
  Of maternal and birth records, 99.3% linked with an NBS record. Mother's country of birth, gestational age (>41 weeks) and lower birthweight were associated with neonatal TSH levels >5 mIU/L. Neonatal and maternal first trimester TSH levels were not correlated, although statistically significant (r = 0.05, P = 0.008). The association between neonatal TSH and maternal TSH, after adjusting for maternal age, gestational age and age at NBS testing, was also small (b = 0.039, P = 0.009).
  
  
  CONCLUSIONS
  Record linkage is a feasible and cost-efficient way to investigate the association between maternal factors and neonatal hormone levels. First trimester maternal thyroid levels are not correlated with neonatal TSH levels. This method of outcome assessment can be used for future research examining long-term outcomes for infants with different NBS results.
authors.affiliation: Clinical and Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Lain
authors.affiliation: Clinical and Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Roberts
authors.affiliation: Disciplines of Genetic Medicine and Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia.|NSW Newborn Screening Programme, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
authors.forename: Bridget
authors.initials: B
authors.lastname: Wilcken
authors.affiliation: Disciplines of Genetic Medicine and Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia.|NSW Newborn Screening Programme, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
authors.forename: Veronica
authors.initials: V
authors.lastname: Wiley
authors.affiliation: Department of Paediatric Endocrinology, Royal North Shore Hospital, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Jack
authors.affiliation: Clinical and Population Perinatal Health Research, Kolling Institute, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Natasha
authors.initials: N
authors.lastname: Nassar
mesh_terms: D000328:Adult; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008498:Medical Record Linkage / Q000379:methods*; D015997:Neonatal Screening / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D013972:Thyrotropin / Q000097:blood*
chemical_list: D013972:Thyrotropin
keywords: newborn; newborn screening; pregnancy; record linkage; thyroxine