Hyperthyroidism (Thyrotoxicosis)
• The most common cause of hyperthyroidism during pregnancy is Graves' disease (95%) (. Since thyroid stimulating antibodies in the circulating IgG structure can cross the placenta, there is a risk of developing hyperthyroidism in the fetus (2-10%).
Pregnancy Outcomes in Women with Thyrotoxicosis
-----------------------Treated and Euthyroid Pregnants------- Uncontrolled Pregnants
Maternal Complications
- Preeclampsia ---------------- 10%------------- 17%
-Heart failure ----------------1 ---------------8%
-Death o 1
Perinatal Complications
-Preterm birth -------------16% ----------32%
-IUGG--------------------------- %11-----------17%
-stillbirth-------------------- 0 ---------------18%
• While propylthiouracil is primarily preferred in treatment; methimazole may cause aplasia cutis, esophageal and choanal atresia (methimazole embryopathy). However, in case of long-term use of propylthiouracil, it is recommended to use propylthiouracil in the first trimester and methimazole from the second trimester due to its hepatotoxicity.
• Radioactive iodine treatment is absolutely contraindicated during pregnancy. Surgical treatment is avoided if possible during pregnancy, but if it is mandatory, the best time is II. trimester.
hypothyroidism
• The most common cause of hypothyroidism during pregnancy is Hashimoto's thyroiditis.
Pregnancy Outcomes in Women with Hypothyroidism  | ||
Complications  | Pregnant women with significant hypothyroidism  | pregnant women with subclinical hypothyroidism  | 
Birth weight < 2000 g 33%  | 33%  | 32%  | 
Preeclampsia 32%  | 32%  | 8%  | 
stillbirth 9%  | 9%  | 3%  | 
Abrupt placenta 8%  | 8%  | 1%  | 
cardiac dysfunction  | 3%  | 2%  | 
• Levothyroxine treatment is started and TSH value should be kept between 0.5-2.5 mU/L.
Postpartum Thyroiditis
• Transient autoimmune thyroiditis is detected in 5-10% of women during the first year after delivery. The tendency to thyroiditis exists before pregnancy and is directly related to the serum thyroid autoantibody level. Postpartum thyroiditis develops in 16% of pregnant women with type 1 diabetes.
• For diagnosis, TSH abnormality (suppressed or low) must be present within one year following birth, excluding thyroid-stimulating antibody positivity (except Graves') or presence of toxic nodules.
• Lymphocytic infiltration is observed and has two defined clinical phases:
► Destructive-induced thyrotoxicosis stage: Due to excessive hormone secretion as a result of glandular destruction
► Hypothyroidism stage: It takes place in 4-8 months postpartum.
• There is an annual risk of 3.6% progression and 30% permanent hypothyroidism. in the next pregnancy There is a 69% risk of recurrence.