Endocrine Abstracts (2011) 26 OC1.3

Maternal thyroid dysfunction during pregnancy and thyroid function of the offspring at the age of 16 years

Fanni Päkkilä1,2, Tuija Männistö1,4, Aini Bloigu3, Marja Vääräsmäki1, Anna-Liisa Hartikainen1, Aimo Ruokonen4, Anneli Pouta3, Marjo-Riitta Järvelin2,5, Heljä-Marja Surcel3 & Eila Suvanto1

1Department of Obstetrics and Gynaecology, Oulu University, Oulu, Finland; 2Institute of Health Sciences, Oulu University, Oulu, Finland; 3Department of Child and Adolescent Health, National Institute for Health and Wellfare, Oulu, Finland; 4Department of Clinical Chemistry, Oulu University, Oulu, Finland; 5Department of Epidemiology and Public Health, Imperial College London, London, UK.

Introduction: Foetus is dependent on maternal thyroid hormone production during the first trimester. Thus, maternal thyroid dysfunction and thyroid antibodies may affect thyroid function of the offspring.

Subjects and methods: We studied a subcohort (n=2000 mother–child-pairs) from a prospective population-based Northern Finland Birth Cohort 1986 (singleton births, total n=9247) covering data throughout pregnancy, childhood and adolescence. The mothers underwent serum sampling in early pregnancy and their offspring at the age of 16 years. Samples were analyzed for thyroid hormones (TSH, free thyroxine (fT4)) and thyroid-peroxidase antibody (TPO-Ab). Mothers were classified according to their thyroid hormone levels and antibody status (euthyroid n=1641, overt and subclinical hypothyroid n=84, overt and subclinical hyperthyroid n=122 and TPO-Ab-positive n=91). The offspring of mothers with thyroid dysfunction were compared to the ones of euthyroid mothers.

Results: The offspring of the hypothyroid mothers had higher TSH and TPO-Ab concentrations than those of the euthyroid mothers (P=0.001 and P=0.02 respectively). When the gender of offspring was taken into account, only the sons of hypothyroid mothers had higher TSH and TPO-Ab concentrations (P=0.004 and P=0.054 respectively). The children of the hyperthyroid mothers had lower TSH than those of the euthyroid mothers (P=0.002).The same was seen when comparing sons and daughters separately (P=0.022 and P=0.041). In the whole subcohort TPO-Ab-positivity was more prevalent among adolescent daughters (8.2%) than sons (4.8%). Especially daughters of TPO-Ab-positive mothers had higher prevalence of positive TPO-Ab than daughters of TPO-Ab-negative mothers (23.1 vs 7.6%, P=0.003), when in sons no significant difference was seen (7.7 vs 4.7%, P=0.310).

Conclusions: The thyroid dysfunction of the mother during pregnancy was associated with altered thyroid hormone levels in her adolescent offspring. TPO-antibodies were more common among the daughters of TPO-Ab-positive mothers. Maternal thyroid dysfunction and antibodies modify thyroid function of the offspring even in adolescence.