title: Maternal early pregnancy and newborn thyroid hormone parameters: the Generation R study.
abstract: BACKGROUND
  Abnormal maternal thyroid parameters are associated with adverse pregnancy outcomes, with consequences for both mother and child. Although various studies have studied maternal thyroid parameters during the first half of pregnancy, little is known about their relations with thyroid parameters of the child.
  
  
  OBJECTIVE
  The objective was to study maternal thyroid parameters during the first half of pregnancy as well as their relations with cord thyroid parameters.
  
  
  METHODS
  Serum TSH, free T(4) (FT4), T(4), and thyroid peroxidase antibody (TPOAb) levels were determined once between gestational wk 9 and 18 in 5393 pregnant women from the population-based Generation R study. Cord serum TSH and FT4 levels were determined in 3036 newborns.
  
  
  RESULTS
  Between gestational wk 9 and 18, the maternal TSH reference range (2.5th to 97.5th percentile) was 0.03-4.04 mU/liter. Gestational age was positively correlated with maternal TSH (r = 0.06, P = 6.3 × 10(-5)) and total T(4) (r = 0.21, P = 1.4 × 10(-44)) and negatively with FT4 (r = -0.27, P=7.3 × 10(-76)) and TPOAb-positivity (r=-0.04, P = 0.01). TPOAb positivity was associated with more subclinical (20.1 vs. 2.4%, P = 1.5 × 10(-39)) and overt hypothyroidism (3.3 vs. 0.1%, P = 1.4 × 10(-10)). Maternal and cord TSH were positively associated (β = 0.47 ± 0.15, P = 1.3 × 10(-5)) as well as maternal and cord FT4 (β = 0.11 ± 0.02, P = 4.5 × 10(-6)).
  
  
  CONCLUSIONS
  We confirm correlations of maternal thyroid parameters with gestational age during the first half of pregnancy and show a substantially increased risk of (subclinical) hypothyroidism in TPOAb-positive mothers. A substantial part of the mothers had a TSH level above 2.5 mU/liter, underlining the importance of using population-specific reference ranges. Maternal and cord thyroid parameters were positively correlated, the exact biological basis of which remains to be determined.
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, 3015 GE Rotterdam, The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: Medici
authors.forename: Yolanda B
authors.initials: YB
authors.lastname: de Rijke
authors.forename: Robin P
authors.initials: RP
authors.lastname: Peeters
authors.forename: Willy
authors.initials: W
authors.lastname: Visser
authors.forename: Sabine M P F
authors.initials: SM
authors.lastname: de Muinck Keizer-Schrama
authors.forename: Vincent V W
authors.initials: VV
authors.lastname: Jaddoe
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
authors.forename: Jacoba J
authors.initials: JJ
authors.lastname: Bongers-Schokking
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Visser
mesh_terms: D000328:Adult; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D005191:Family Characteristics; D005260:Female; D005312:Fetal Blood / Q000737:chemistry / Q000378:metabolism; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D033261:Maternal-Fetal Relations; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood* / Q000378:metabolism; D011262:Pregnancy Trimester, Second / Q000097:blood / Q000378:metabolism; D011297:Prenatal Exposure Delayed Effects / Q000097:blood; D012016:Reference Values; D013963:Thyroid Hormones / Q000032:analysis / Q000097:blood* / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood; D055815:Young Adult
chemical_list: D013963:Thyroid Hormones; D013972:Thyrotropin