title: Do maternal factors influence neonatal thyroid status in the extreme premature infant?
abstract: BACKGROUND
  In early pregnancy, maternal transfer of thyroxine (T4) significantly contributes to the foetal T4 requirements. Interruption of the maternal transfer of T4 may lead to inadequate T4 exposure, potentially leading to neurodevelopmental deficits.
  
  
  OBJECTIVE
  To determine if maternal factors are associated with the thyroid hormone status of extremely premature infants during the first five days of life.
  
  
  METHODS
  This prospective study looked at 117 mothers and their extremely premature babies (born before 28 weeks' gestation). The relationship between neonatal thyroid hormone status and maternal factors (gestation, route of delivery, exogenous maternal glucocorticoid administration, maternal free T4 (FT4), presence or absence of maternal chorioamnionitis, maternal smoking status, maternal body mass index (BMI) index, maternal thyroid peroxidase antibody status (TPO) and maternal haemoglobin levels) were evaluated. Multiple linear regression was used to study independent factors affecting neonatal thyroid function.
  
  
  RESULTS
  Mean gestational age was 25(+5) ± 1.3 weeks (range 22(+0) to 27(+6)). Neonatal FT4 strongly correlated with gestation, with a greater severity of hypothyroxinaemia associated with lower gestation (r = 0.6, p < 0.0001). Multiple regression found gestation to be the only independent factors affecting thyroid status (beta coefficient = 0.08, p = 0.01), and no maternal factors were found to be associated with neonatal thyroid status.
  
  
  CONCLUSIONS
  Neonatal thyroid status in extreme preterm infants is independently affected by gestation and not maternal factors such as route of delivery, exogenous maternal glucocorticoid administration, third trimester maternal FT4, presence or absence of chorioamnionitis, smoking status, BMI, TPO status or haemoglobin levels. The severity of neonatal hypothyroxinaemia increases with lower gestational age.
authors.affiliation: a Department of Women's and Children's Health , Institute of Translational Medicine, University of Liverpool , Liverpool , UK and.
authors.forename: Sze M
authors.initials: SM
authors.lastname: Ng
authors.forename: Gabriella
authors.initials: G
authors.lastname: Watson
authors.forename: Mark A
authors.initials: MA
authors.lastname: Turner
authors.forename: Paul
authors.initials: P
authors.lastname: Newland
authors.forename: A Michael
authors.initials: AM
authors.lastname: Weindling
mesh_terms: D005260:Female; D006801:Humans; D062071:Infant, Extremely Premature / Q000502:physiology*; D007231:Infant, Newborn; D008297:Male; D008431:Maternal-Fetal Exchange / Q000502:physiology; D009035:Mothers / Q000706:statistics & numerical data; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology*; D047928:Premature Birth / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013963:Thyroid Hormones / Q000097:blood
chemical_list: D013963:Thyroid Hormones
keywords: Maternal; prematurity; thyroid