Causes and ways to prevent hypothyroidism during pregnancy

The article was professionally consulted by Specialist Doctor II Pham Thi Tuyet Mai - Obstetrician and Gynecologist - Department of Obstetrics and Gynecology - Vinmec Hai Phong International General Hospital.

In the human body, the thyroid gland is an important endocrine gland, with the function of regulating the body's metabolism. During pregnancy, the thyroid gland increases iodine intake to ensure normal levels of thyroid hormone production. Therefore, in pregnant women whose diets do not contain enough iodine in their daily diet, the thyroid gland may enlarge during pregnancy.
Hypothyroidism during pregnancy is when the function of the thyroid gland is disturbed, the amount of thyroid hormone is not released enough, leading to a decrease in the level of thyroid hormone in the blood causing hypothyroidism. Hypothyroidism during pregnancy accounts for about 1% of pregnant women.
Hypothyroidism during pregnancy affects both mother and baby as follows:
Affects pregnant women: Possible complications of hypothyroidism such as sluggishness, anemia, constipation, congestive heart failure bleeding, muscle weakness... And also complications of obstetrics including: pre-eclampsia, postpartum bleeding,... Severe cases can lead to miscarriage. Effects on the fetus: Causes birth defects, cretinism, easy miscarriage, stillbirth. Children with congenital hypothyroidism can experience abnormalities in intellectual and physical development, if not detected and treated promptly.

The most common cause of hypothyroidism during pregnancy is Hashimoto's disease, an autoimmune disease caused by chronic thyroiditis.
Other causes of hypothyroidism include:
Pregnant women who have had their thyroid removed. Pregnant women are being treated with radioactive iodine. Pregnant women are being treated with Graves with high-dose synthetic antithyroid drugs. People with high risk factors for hypothyroidism include:
A family history of hypothyroidism. Pregnant women with goiter. The mother has had thyroiditis. Hypothyroidism in a previous pregnancy. Iodine-deficient diet.

Need to coordinate internists and obstetricians to monitor pregnancy and treat diseases.
Treatment of hypothyroidism in pregnant women is the same as in non-pregnant women, by supplementing with a synthetic form of thyroid hormone.
It is best and safest for pregnant women to be adjusted to the optimal dose, reaching euthyroidism from before pregnancy.
Thyroid function test (FT4 and TSH) should be tested every 4-6 weeks (at each prenatal visit). If the dose of Levothyroxine has to be changed, it should be rechecked after 4 weeks. The goal is to ensure that FT4 and TSH levels are within normal limits.
For those who already have hypothyroidism and are being treated with thyroid hormone (Levothyroxine), when they know they are pregnant, they need to do FT4 and TSH tests immediately and monthly during pregnancy because the need for thyroid hormone increases. During pregnancy, an increase in the dose of the drug is required.
Immediately after delivery, the patient should return to the pre-pregnancy dose. Prenatal iron-containing vitamins may decrease the absorption of thyroid hormone from the gastrointestinal tract. Therefore, these two drugs should be taken at least 2-3 hours apart.
If the person does not have thyroid disease and the first TSH test after pregnancy is normal, there is almost no need to check the thyroid status again.

Hypothyroidism during pregnancy causes dangerous complications for both mother and baby. Therefore, pregnant mothers need to know how to prevent hypothyroidism to stay healthy throughout pregnancy. Some measures to prevent hypothyroidism during pregnancy include:
In daily meals, use iodized salt instead of regular salt. Pregnant women need to choose iodine-rich foods such as sea fish, eggs, milk, dark green vegetables, yellow ripe fruits... Before adding salt to the soup, let it cool down to avoid evaporation. Because iodine is very volatile when exposed to high temperature. From adolescence, if a goiter is detected, it must be treated early even if it is a simple goiter. Mothers in the first 3 months of pregnancy and women who want to become pregnant need to be screened. Especially in women at risk of hypothyroidism. Women with thyroid disease if they want to get pregnant, it is best to stabilize the disease until it is completely cured. While being treated for the disease, if you have an unwanted pregnancy but want to keep the pregnancy, you should immediately go to a medical facility for an endocrinology examination to be consulted and give the best advice. Newborn screening right after birth to detect cases of congenital hypothyroidism early so that the child can be treated early, avoiding long-term consequences. In summary, the cause of hypothyroidism during pregnancy is still unknown, but it leaves dangerous complications for both mother and baby. To prevent hypothyroidism well during pregnancy, pregnant women need to have a reasonable diet, supplement with enough iodine by using iodized salt instead of normal salt in their daily meals. Screening during the first trimester of pregnancy, especially in women with high-risk factors. In addition, newborns also need to be screened for early disease detection and prompt treatment.