Influence of frequency of previous pregnancies on the prevalence of thyroid nodules in women without clinical evidence of thyroid disease.
In a region with insufficient alimentary iodine supply (Kiel, Northern Germany) the prevalence of thyroid nodules was studied by means of ultrasonography in 212 healthy women (36-50 years old) in four groups of 53 women each with 0, 1, 2, and 3-5 previous pregnancies. Goiters were found in 28.3% (15 of 53) of the women without children and in 28.9% (46 of 159) of the women with children. There was no significant increase of goiter prevalence according to the number of pregnancies. We detected thyroid nodules in 21.2% (45 of 212). Only 9.4% (5 of 53) of the women without previous pregnancies had thyroid nodules, but 25.1% (40 of 159) of the women with pregnancies in the past had nodules, the difference being statistically significant (p < 0.05). We observed nodules in 11 of 53 women with 1 child (20.7%), in 11 of 53 women with 2 children (20.7%), and in 18 of 53 women with 3-5 previous pregnancies (33.9%). We propose that, in regions with borderline or insufficient alimentary iodine supply, accentuated iodine deficiency during pregnancies due to increase of iodine requirement is a probable cause for the higher prevalence of thyroid nodules in women with previous pregnancies.
Department of Internal Medicine, University of Kiel, Federal Republic of Germany.
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D000328:Adult; D005260:Female; D006042:Goiter / Q000000981:diagnostic imaging / Q000453:epidemiology; D006801:Humans; D007455:Iodine / Q000172:deficiency; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications; D016606:Thyroid Nodule / Q000453:epidemiology* / Q000209:etiology / Q000648:ultrastructure; D014463:Ultrasonography
D007455:Iodine