Graves’ disease: what impact on pregnancy?

What is Graves’ disease?

Graves’ disease is a autoimmune disease in which the immune system attacks the thyroid gland. The latter is a small endocrine organ located at the base of the neck, which secretes thyroid hormones necessary for the proper functioning of the body.

In detail, the body of a person with Graves’ disease makes antibodies against thyroid stimulating hormone receptors, or TSH, which activates the secretion of the thyroid hormones T3 and T4. An overproduction that the body cannot regulate, which causes hyperthyroidism.

Unlike other forms of hyperthyroidism, Graves’ disease rather progresses in phases, with periods of relapses and remissions that are difficult or even impossible to predict.

Note that, although it is not yet clear why, Graves’ disease affects women on average six times more than men.

What are the symptoms of Graves’ disease?

The symptoms of Graves’ disease are similar to those of hyperthyroidism, although they can occur more suddenly:

• unexplained weight loss, without decrease in food volume;
• unexplained fatigue;
• heart palpitations and tachycardia;
• sweats;
• permanent thirst;
• nervousness and irritability;
• difficulty concentrating;
• swollen, red or even watery eyes (we speak of dysthyroid orbitopathy);
• presence of a lump at the base of the neck (goiter).

Faced with such symptoms, to make the diagnosis, the doctor usually prescribes a blood test to measure the thyroid hormones (TSH, T3 and T4) and the antibodies present. A thyroid ultrasound or scan may also be done to look at the thyroid gland.

note that Graves’ disease may go unnoticed during pregnancy (if it has not been diagnosed before), but also manifested by symptoms such as the absence of weight gain despite a normal diet, or even weight loss contrasting with a preserved appetite, and a permanent tachycardia greater than 90 beats per minute. The other signs of hyperthyroidism, such as goiter, fatigue or difficulty concentrating, can unfortunately be confused with the symptoms of pregnancy, and therefore go unnoticed.

Graves’ disease: what is the treatment?

Strictly speaking, there is no curative treatment for Graves’ disease. Support includes three different options, each with their own set of advantages and disadvantages. Drug treatment of antithyroid drugs aimed at blocking the production of thyroid hormones may be suggested. Destruction of thyroid cells by radioactive iodine is a second approach, while the third approach is surgical and consists of the outright removal of the thyroid gland (thyroidectomy). But this involves taking synthetic hormones for life, to replace lost thyroid function.

Note that the presence of Graves’ disease before or during pregnancy must obviously give rise to a very specific medical follow-up, in order to ensure that the drugs and treatments against the disease are not harmful to the fetus. Treatment with radioactive iodine is obviously to be avoided in pregnant women. Medicines should be adapted as best as possible so as not to interfere with the thyroid function of the unborn baby. The practitioner will thus choose drugs that cross the placental barrier little, if at all., to limit their effects on fetal development, drugs whose doses should be limited as much as possible.

Hyperthyroidism, hypothyroidism and pregnancy: what are the risks?

Hypothyroidism, like hyperthyroidism, is not without risk for the good progress of the pregnancy and the health of the fetus, especially in the absence of treatment and adequate care.

Hypothyroidism and hyperthyroidism can thus lead to miscarriage, hypertension, pre-eclampsia, premature delivery, delayed fetal growth, or retarded psychomotor development of the future baby.

During pregnancy, thyroid problems should be closely monitored, especially by regular hormone tests for TSH, and the processing adjusted accordingly. And the fetus is generally monitored by ultrasound, in particular to look for a possible goiter, sign of hyperthyroidism, or on the contrary signs of hypothyroidism.

Graves’ disease and desire for pregnancy

It is quite possible to consider pregnancy if you have Graves’ disease. The main thing being to make arrangements in advance, and to be well monitored once you are pregnant, so that the treatment is adapted accordingly. There are indeed antithyroid drugs which can cause fetal malformations, and others which are preferable because of their less transplacental passage.

Dance an article dated March 1, 2017, review Prescribe indicated that “synthetic antithyroid drugs“Constitute”the treatment of choice”Of Graves’ disease during pregnancy. The review specified, however, that insofar as these drugs “cross the placenta and block the functioning of the fetal thyroid“, they must be used “at the smallest effective dose“. In detail, the medical journal Prescribe indicated that:

• “in the first trimester, propylthiouracil is the first choice, as the malformations seemed less severe and rarer than with carbimazole or thiamazol”;
• “in the second and third trimesters, if stopping the antithyroid drug is impossible, the risks of hepatic damage linked to propylthiouracil are an argument for replacing it with carbimazole or thiamazol“.

Whatever treatment is prescribed, regular monitoring of the fetus is essentialbecause he is exposed to both prescribed antithyroid drugs and maternal thyroid stimulating antibodies.

It is otherwise not recommended to modify or stop treatment without prior medical advice.

Thyrotoxicosis, that is to say the set of symptoms due to hyperthyroidism, would affect 2 to 10% of children born to mothers with or having presented Graves’ disease.

How does Graves’ disease progress in pregnant women?

Like other immune diseases, Graves’ disease tends to get better in pregnant women, because pregnancy corresponds to a state of relative immunosuppression. Clearly, the immune system of pregnant women is somewhat weakened compared to before pregnancy, in particular to prevent the body from rejecting the fetus. Because it is an autoimmune disorder, the hyperthyroidism resulting from Graves’ disease therefore generally tends to decrease, especially during the second half of pregnancy. The beginning of pregnancy or the postpartum period would, on the other hand, be favorable periods for the worsening of the disease or for a relapse.

Graves’ disease and breastfeeding: not necessarily incompatible

Breastfeeding is generally not recommended in case of treatment with a synthetic antithyroid drug, due to their passage into breast milk. Just as there are anti-thyroid drugs that are not recommended during pregnancy, there are treatments for Graves’ disease that are contraindicated during breastfeeding. However, with close monitoring of the infant, the use of low dose propylthiouracil (PTU) is possible in nursing women.

According to the Reference Center for Teratogenic Agents (CRAT), “the quantity of propylthiouracil ingested via milk is very low: the child receives less than 1% of the maternal dose (in mg / kg) (calculation carried out on a small number of people)”. Besides, “no particular event”, In particular of a hepatic nature,“has not been reported to date in about twenty breastfed children of mothers mostly receiving a dose of around 300 mg / day and a maximum of 750 mg / day, in particular no impact on their thyroid function“.

As we have seen, if pregnancy and breastfeeding occur after surgical removal of the thyroid, thyroid hormone intake is required for life. As in the case of hypothyroidism (where the basic treatment is levothyroxine), this thyroid hormone intake may be compatible with breastfeeding, under close medical supervision.