Impact of Thyroid Autoimmunity on Pregnancy in Iodine-Sufficient Areas

Objectives: Pregnancy has a profound impact on maternal thyroid morpho-functionality; thus, thyroid dysfunction can cause multiple perinatal risks and complications. The aim of the study is to determine the incidence of maternal thyroid autoimmunity and dysfunction, their influence on some gestational and perinatal parameters of the newborn, and the impact of iodine status on thyroid autoimmunity in a region with sufficient iodine intake.

Material and method: Retrospective study conducted on a number of 74 full-term pregnancies with singletons, pregnant women originating from the perimarine area of Romania. The participants were divided into 2 groups: group 1 - pregnant with chronic autoimmune thyroiditis and subclinical/clinical manifest hypothyroidism; group 2 - pregnant without thyroid pathology considered as a control group. Maternal variables studied: dosage of thyroid hormone and antithyroid autoantibodies, median urinary iodine concentration; and for the newborns: birth weight, APGAR score, gestational age, incidence of perinatal events. The administration of iodine supplements during pregnancy was monitored.

Results: The incidence of chronic autoimmune thyroiditis was 36.4%. Maternal thyroid autoimmunity is associated with low birth weight and premature birth compared to the control group. The predominant perinatal pathology among pregnant women with thyroid autoimmunity was represented by spontaneous abortion, presenting a 2.8x higher risk compared to the control group. Median urinary iodine concentration was under 150 mcg/L in both studied groups of pregnant women. Iodine nutritional deficiency, but also excess iodine intake, were positively correlated with maternal thyroid autoimmunity. Consumption of iodine supplements and iodized salt was reduced in the category of pregnant women with thyroid autoimmunity.

Conclusions: Thyroid autoimmunity during pregnancy presents significant challenges even in iodine-sufficient geographical areas. Maternal autoimmune thyroiditis represents a risk factor with effects on fetal development and repercussions in the perinatal period. Evaluation of thyroid function parameters before conception or in the first weeks of pregnancy is recommended as a diagnostic and prophylactic measure.