title: Neonatal thyroid function born to mothers living with long-term excessive iodine intake from drinking water.
abstract: OBJECTIVE
  The effects of long-term excessive maternal iodine intake on neonatal thyroid function are less known. This study aimed to assess the effects of maternal excessive iodine intake from drinking water on thyroid functions of both mothers and their neonates.
  
  
  METHODS
  This observational study was performed in high iodine (HI) areas and adequate iodine (AI) intake areas, including 384 healthy pregnant women in late gestation (mean week 39·3 ± 1·6 weeks) and their newborns. Blood and urine samples were obtained from pregnant women, while cord blood samples were obtained from neonates. Urinary iodine concentration (UIC) and thyroid function were evaluated.
  
  
  RESULTS
  The median maternal UIC was 1241 and 217 μg/l in HI and AI areas, respectively (P < 0·001). The concentrations of serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) in neonates in HI areas were 7·33 mIU/l (range 5·47, 11·06 mIU/l), 2·93 ± 0·59 and 15·03 ± 1·92 pmol/l, respectively, while that were 4·71 mIU/l (range 3·96, 6·04 mIU/l), 2·31 ± 0·28 and 16·50 ± 1·35 pmol/l in AI neonates (P < 0·05). Similar changes were also observed in neonates in HI areas when excluding the effect of maternal thyroid autoimmunity. Cord blood TSH concentration (r = 0·31, P = 0·001) and FT3 concentration (r = 0·43, P = 0·001) were positively correlated with maternal UIC. Cord blood FT4 concentration was negatively correlated with maternal UIC (r = -0·25, P = 0·001). Mothers living in HI areas (β = 0·296, 95% CI: 0·163, 0·255) and with subclinical hypothyroidism (β = 0·360, 95% CI: 0·034, 0·175) contributed to elevated cord blood TSH concentration in neonates, while male neonates were more likely to present with higher TSH concentration compared with female infants (β = -0·760, 95% CI: -0·119, -0·033).
  
  
  CONCLUSIONS
  Excessive iodine intake during pregnancy was associated with an increased rate of hyperthyrotropinaemia in neonates and their mothers, especially in male neonates.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Zhongna
authors.initials: Z
authors.lastname: Sang
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Long
authors.initials: L
authors.lastname: Tan
authors.affiliation: Haixing Hospital, Heibei Province, China.
authors.forename: Shufen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Dong
authors.affiliation: Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Zanjun
authors.initials: Z
authors.lastname: Chu
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Guiqin
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Zhaixiao
authors.initials: Z
authors.lastname: Yao
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Shen
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Tianjin Medical University, Tianjin, China.
authors.forename: Wanqi
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000328:Adult; D002681:China; D003430:Cross-Sectional Studies; D060766:Drinking Water / Q000737:chemistry*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005843:Geography; D006801:Humans; D007231:Infant, Newborn; D007455:Iodine / Q000008:administration & dosage / Q000009:adverse effects* / Q000652:urine; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood / Q000139:chemically induced* / Q000652:urine; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects* / Q000503:physiopathology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
chemical_list: D060766:Drinking Water; D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine