Thyroid dysfunction and autoantibodies during pregnancy as predictive factors of pregnancy complications and maternal morbidity in later life

Abstract

Context: Knowledge is scarce concerning the significance of thyroid dysfunction/antibodies during pregnancy in regard to pregnancy complications/later maternal morbidity.

Objective: The aim of this study was to evaluate the association between maternal thyroid dysfunction/antibodies during pregnancy and pregnancy complications or later maternal hypertension, diabetes, and thyroid disease.

Design and setting: We studied a prospective population-based cohort, Northern Finland Birth Cohort 1986 (NFBC 1986), with follow-up of 20 yr. Medication and hospital discharge records were used to assess maternal morbidity to hypertension, diabetes, and thyroid diseases.

Participants: The study consisted of mothers of NFBC 1986 with early pregnancy serum samples for thyroid function and antibody analyses (n = 5805). Mothers were grouped and compared according to these test results.

Main outcome measures: We focused on preeclampsia and gestational diabetes during index pregnancy, later maternal hypertension, diabetes, and thyroid disease morbidity and total mortality.

Results: Thyroid dysfunction and antibodies were not associated with pregnancy complications. Overt hypothyroidism was associated with subsequent maternal thyroid disease [hazard ratio (HR) (95% confidence interval), 17.7 (7.8-40.6)] and diabetes [6.0 (2.2-16.4)]. Subclinical hypothyroidism [3.3 (1.6-6.9)], TPO-Ab-positivity [4.2 (2.3-7.4)], and TG-Ab-positivity [3.3 (1.9-6.0)] were also associated with later thyroid disease. No association was found between thyroid dysfunction/antibodies and hypertension or overall mortality.

Conclusions: Thyroid dysfunction and antibodies during pregnancy seem to predict later thyroid disease. Overt hypothyroidism poses risk of diabetes.