Doctor endocrinologist checking thyroid pregnant

Thyroid and Pregnancy: an overview

By Cristiano Antonino On Jan 3, 2023

Thyroid and pregnancy: the hormone glands produce quantities of hormones appropriate to the body’s demands at that particular time. In this context, pregnancy is the best known condition as far as the thyroid gland is concerned

During gestation, several events occur that lead to an increased demand for thyroid hormone (up to 50% more) and a parallel depletion of maternal iodine.

These mechanisms are particularly present in the very first weeks of gestation.

The physiological adaptations that occur during gestation can lead to a condition of iodine deficiency even in a woman with an adequate pre-pregnancy iodine intake.

Thyroid functions: a situation of iodine deficiency in pregnancy continues even during breastfeeding

In view of these changes, it is therefore important to monitor iodine intake and, if necessary, correct a deficient condition.

Thyroid monitoring in pregnancy is therefore based on periodic iodide assays, accompanied by ultrasound checks to assess maternal thyroid volume.

Under conditions of normal iodine intake during pregnancy, there should in fact be no increase in thyroid volume.

In addition to the aforementioned physiological adaptations, the thyroid must necessarily be studied prior to pregnancy.

This is necessary in order to avoid the risk of miscarriage especially during the very first weeks of gestation.

Conditions such as hypothyroidism, hyperthyroidism, Hashimoto’s thyroiditis and the presence of thyroid nodules must in fact be excluded before conception.

If present, they must be closely monitored and corrected even before pregnancy.

Lastly, due to their increasing popularity, ovarian stimulation, which is practised to achieve pregnancy, is an important indication for endocrinological examination.

Indeed, several scientific studies show how the increased amount of female sex hormones that occurs after ovarian stimulation can lead to a further depletion of thyroid hormone, and thus a failure to maintain the pregnancy itself.

This eventuality can only be greatly prevented if it is known before treatment.

In conclusion, the best strategy is to assess, as suggested by several European and American guidelines, thyroid function and iodine intake in women of childbearing age who are seeking pregnancy.

In the case of planned pregnancies and/or pregnancies achieved after hormonal stimulation, thyroid evaluation is strongly recommended before any kind of gynaecological treatment.