Document Detail


Smoking and early pregnancy thyroid hormone and anti-thyroid antibody levels in euthyroid mothers of the Northern Finland Birth Cohort 1986.
MedLine Citation:
PMID:  22873201     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Smokers in the general population have lower thyrotropin (TSH) and higher free triiodothyronine (fT3) and free thyroxine (fT4) concentrations, but the results in pregnant population vary from no effect to a decrease in TSH and fT4 concentrations and an increase in fT3 levels. Our objective was to further evaluate the question of whether there is an association between smoking, before and during pregnancy, with maternal thyroid function during pregnancy and with the risk for subsequent hypothyroidism.
METHODS: Our study population was a prospective population-based cohort (N=9362), the Northern Finland Birth Cohort 1986, with extensive data throughout gestation. The mothers underwent serum sampling in early pregnancy. The samples were assayed for TSH, fT3, fT4, thyroid-peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (TG-Abs) (n=5805). Mothers with thyroid dysfunction diagnosed before or during pregnancy were excluded, leaving 4837 euthyroid mothers. The smoking status of mothers and fathers were requested by questionnaires during pregnancy. Subsequent maternal morbidity relating to hypothyroidism 20 years after the index pregnancy was evaluated using national registers.
RESULTS: Euthyroid mothers who smoked before, or continued smoking during first trimester of pregnancy, had higher serum fT3 (p<0.001) and lower fT4 (p=0.023) concentrations than nonsmokers. Smoking in the second trimester was associated with higher fT3 (p<0.001) concentrations, but no difference in fT4 concentrations compared with nonsmokers. TG-Abs were less common among smoking than nonsmoking mothers (2.5% vs. 4.7%, p<0.001), but the prevalence of TPO-Ab was similar. Paternal smoking had no independent effect on maternal early pregnancy thyroid hormone or antibody concentrations. The risk of subsequent maternal hypothyroidism after follow-up of 20 years was similar among prepregnancy smokers and nonsmokers.
CONCLUSIONS: In euthyroid women, smoking during pregnancy was associated with higher fT3 levels and lower fT4 levels; possibly reflecting smoking-induced changes in peripheral metabolism of thyroid hormones. No differences were found in TSH concentrations between smokers and nonsmokers. Our results differ from those of the general population, which usually have shown smoking-induced thyroidal stimulation. This is possibly due to pregnancy-induced changes in thyroid function. Decreases in fT4 levels among smokers might predispose to hypothyroidism or hypothyroxinemia during pregnancy. Despite these changes in thyroid function, smoking did not increase the woman's risk of subsequent hypothyroidism.
Authors:
Tuija Männistö; Anna-Liisa Hartikainen; Marja Vääräsmäki; Aini Bloigu; Heljä-Marja Surcel; Anneli Pouta; Marjo-Riitta Järvelin; Aimo Ruokonen; Eila Suvanto
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-08-08
Journal Detail:
Title:  Thyroid : official journal of the American Thyroid Association     Volume:  22     ISSN:  1557-9077     ISO Abbreviation:  Thyroid     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-08-28     Completed Date:  2013-02-04     Revised Date:  2013-09-03    
Medline Journal Info:
Nlm Unique ID:  9104317     Medline TA:  Thyroid     Country:  United States    
Other Details:
Languages:  eng     Pagination:  944-50     Citation Subset:  IM    
Affiliation:
Department of Clinical Chemistry, University of Oulu, Oulu, Finland.
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MeSH Terms
Descriptor/Qualifier:
Adult
Autoantibodies / blood*
Autoantigens / immunology
Female
Finland / epidemiology
Humans
Hypothyroidism / blood,  epidemiology,  etiology
Iodide Peroxidase / immunology
Iron-Binding Proteins / immunology
Maternal Behavior
Paternal Behavior
Pregnancy
Pregnancy Trimester, First
Prevalence
Prospective Studies
Risk
Smoking / adverse effects,  blood*,  epidemiology
Thyroid Function Tests
Thyroid Gland / immunology*
Thyroxine / blood*
Triiodothyronine / blood*
Young Adult
Chemical
Reg. No./Substance:
0/Autoantibodies; 0/Autoantigens; 0/Iron-Binding Proteins; 0/anti-thyroglobulin; 6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine; EC 1.11.1.7/TPO protein, human; EC 1.11.1.8/Iodide Peroxidase
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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