THYROID VOLUME IN HEALTHY PREGNANT WOMEN FROM PLOVDIV REGION
Keywords:
pregnancy, thyroid gland, thyroid volume, тhyroid dysfunction, TSH, PlovdivAbstract
Pregnancy is a stress for the thyroid gland because during this period significant changes occur in the
thyroid gland and its function. During pregnancy, the thyroid gland increases in size by 10% in iodine-rich
countries, and by 20% to 40% in iodine-deficient areas. This hyperplasia is likely related to autoregulatory
mechanisms of iodine on thyroid growth, and it has been suggested that in fact thyroid volume and function during
pregnancy are physiologically adapted to meet increased iodine and energy demands. The aim of the study is to
reveal the morphological features of the thyroid gland of healthy pregnant women in the different stages of
pregnancy and to analyze the dynamics in the volume and structure of the gland in the context of physiological
changes in thyroid function. 120 pregnant women from the Plovdiv region over the age of 18, respectively from the
first, second and third trimester of pregnancy, were observed. The average age of pregnant women is 28 years. All
participants were selected according to inclusion and exclusion criteria defined for the aims of this study. All women
had a negative history of thyroid disease, proper iodine prophylaxis, and negative titers for thyroid antibodies
(TPOAb, TgAb). Software products - IBM SPSS 26 - were used for statistical processing of the obtained data. The
statistical analysis was performed according to the guidelines of the Institute of Clinical and Laboratory Standards
(CLSI). A positive opinion was received from the Commission on Scientific Ethics at Medical University of Plovdiv
(№ Р-172 / 21.01.2020). The study included 120 pregnant women for each trimester of pregnancy. Thyroid volume
during the first trimester of pregnancy averaged 7.19 ± 1.73 ml (mean±SD), with a minimum measured value of
4.12 ml and a maximum of 9.90 ml. The volume of the thyroid gland during the second trimester of pregnancy was
on average 7.57±1.95 ml (mean ± SD), with the minimum measured value being 4.27 ml and the maximum 11.50
ml. Thyroid volume during the third trimester of pregnancy averaged 7.60 ± 1.70 ml (mean±SD), with a minimum
measured value of 5.09 ml and a maximum of 11.69 ml. The volume of the thyroid gland was established by
sonography. A standard formula was used to calculate thyroid volumes in ml. According to the World Health
Organization (WHO), the normal thyroid volume in women should be between 4.4-18 ml. According to M.
Boyanov, in healthy women (15-74 years of age) from the Bulgarian population, the norm for the average volume of
the thyroid gland is 12.4±3.34 mL (9.06-15.74 mL). A slight increase in all observed parameters was found in the
second and third trimesters compared to the first. In most pregnant women, the thyroid volume remains within the
limits recommended by the World Health Organization. The slight increase in thyroid volume during the second and
third trimesters is probably the result of physiological adaptation of the gland.
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