Can you still get pregnant if you have hypothyroidism? Here are six questions you need to know!

Author: Xiao Jianzhong, Chief Physician of Beijing Tsinghua Chang Gung Hospital affiliated to Tsinghua University

Reviewer: Wu Xueyan, Chief Physician, Peking Union Medical College Hospital

As we all know, one of the main causes of hypothyroidism is Hashimoto's thyroiditis. Among women of childbearing age, about 10%-15% have Hashimoto's thyroiditis, so there are also relatively many women of childbearing age with hypothyroidism.

Regarding hypothyroidism, we need to understand the following issues:

First, you can get pregnant even if you have hypothyroidism.

It is generally recommended to adjust hormone levels to the normal range before pregnancy. What is considered normal? TSH (thyroid stimulating hormone) below 4mIU/L is considered normal, but if there is hypothyroidism, it is recommended to control TSH below 2.5mIU/L. It is better to get pregnant at this time (in recent years, it has also been suggested to relax to 4.0mIU/L).

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Second, if you become pregnant while taking medication to treat hypothyroidism, it generally will not affect the health of the baby.

The drug for treating hypothyroidism is now generally levothyroxine sodium, which has the same chemical structure as T4 secreted by our body, so taking this drug in moderation has no effect on children. And levothyroxine sodium has a very good feature. There are two main forms of thyroid hormone in the human body, one is T4 and the other is T3. T3 has higher function and activity than T4, and the body can control the conversion of T4 to T3 according to its own needs. Therefore, it is rare to take too much levothyroxine sodium. If the amount is slightly more, the body can adjust itself and reduce the conversion to T3. There will only be problems if you take too much.

Third, pregnancy may aggravate hypothyroidism.

Because during pregnancy, there is one more person who needs to use thyroid hormone, the body's need for thyroid hormone will increase. If it cannot be produced, the symptoms of hypothyroidism, including the test indicators of hypothyroidism, will become more obvious. Therefore, after pregnancy, especially in the first few months, thyroid function may need to be checked every 3-4 weeks.

In addition, you also need to pay attention to the fact that, for example, if you had hypothyroidism before pregnancy, it was well controlled by taking drugs such as levothyroxine sodium. However, you must remember that the dosage may need to be increased by 50%-100% after pregnancy, so you should also go for regular checkups and adjust the dosage according to the examination results.

Fourth, women with hypothyroidism who have been taking medication for a long time cannot stop taking the medication to treat hypothyroidism after pregnancy.

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The reason why you need to take levothyroxine sodium tablets is because you don't produce enough thyroxine and need to supplement it. When you are pregnant, you need more thyroxine. At this time, you should not only continue to take it, but also determine whether to increase the dosage based on the test results.

Everyone says that it is not good to take medicine during pregnancy. It depends on what kind of medicine it is. Some medicines have an impact on the development of the fetus, so you should definitely avoid taking them if you can. But if it is a medicine that is good for the development of the fetus, you must insist on taking it and cannot stop.

Fifth, pregnant women with hypothyroidism should have their thyroid function checked regularly.

When it comes to the frequency of inspection, we need to consider one issue, which is whether the thyroid hormone is metabolized quickly or slowly. If it is metabolized very quickly, you may need to check more frequently. Here we need to understand a concept - half-life. Half-life refers to the time it takes for the concentration of a drug to drop from its peak to half after entering the human blood. The half-life of thyroid hormone is about 1 week.

Therefore, we do not recommend frequent testing, unless it is in the early stages, when hypothyroidism is very severe and the doctor is afraid to prescribe a large dose, so it is necessary to test once every 2 weeks. Usually, it is more reasonable to test once every 4 weeks. If it is in the second half of the stage and the dose is adjusted more steadily, it is enough to test once every 6-8 weeks.

Sixth, hypothyroidism has a genetic susceptibility.

Most cases of hypothyroidism are caused by autoimmune disorders, which are related to genes. Whether it is before or during pregnancy, or even after giving birth, some mothers develop thyroid disease. Her genes are always with her. Compared with ordinary children, this child will have a significantly higher probability of hypothyroidism in his lifetime, but usually the disease will not occur until after puberty.

One slightly different thing here is that the incidence of autoimmune diseases in women and men is different. For example, the incidence of thyroid disease in women is about 3 times higher than that in men. So if a girl is born, especially after puberty, you may need to pay more attention to this issue because she is at greater risk; if a boy is born, the risk is relatively much smaller, but it may also happen.