الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Thyroid hormones are necessary for the reproductive system to function properly and for normal pregnancy. Alterations in thyroid physiology has been linked to reproductive dysfunctions as menstrual irregularities, ovulation disturbances, infertility as well as poor pregnancy outcomes such as miscarriage, preterm delivery, and fetal developmental abnormalities.
Interactions between hypothalamus-pituitary-thyroid and hypothalamus-pituitary-gonadal axis occur at multiple levels. Thyroid hormones play a potential intracrine and paracrine role through thyroid hormone stimulating hormone receptors and thyroid hormone receptors present in the ovaries. Even minor alterations of the highly regulated local activity of TH, even in euthyroid status, can significantly impact early pregnancy and may cause pregnancy loss.
Assisted reproduction technology is widely used as the ultimate approach to treat certain causes of infertility. In the case of IVF /ICSI, ovarian stimulation protocols are necessary in the ART procedure utilizing gonadotropin-releasing hormone agonists or antagonists along with FSH to induce the production of a high number of oocytes capable for fertilization and subsequent embryogenesis.
Regarding the relationship between thyroid and ART, it has been suggested that ovarian stimulation potentially impacts thyroid function, and this change may result in adverse reproductive outcomes. However, the routine monitoring of thyroid function during controlled ovarian stimulation remains controversial. To address this clinical question, our study aimed to evaluate the effect of controlled ovarian stimulation on thyroid function in euthyroid infertile women with and without thyroid autoimmunity.
Eighty euthyroid females scheduled for IVF/ICSI were enrolled in our study. TSH and fT4 levels were evaluated in three different time points during OS (baseline, at time of trigger and 16 days after trigger). Thyroid autoimmunity was assessed by measuring Anti-TPO levels before OS. A comparative analysis between thyroid hormone levels in women with and without thyroid autoimmunity in the three time points was performed.
Our results showed a significant increase of TSH levels during OS especially 16 days after trigger (the same day of pregnancy test) while fT4 levels showed subtle decrease during OS which was not statistically significant.
Although this study was not aiming to explain the exact mechanisms underlying this phenomenon, some interesting information can be retrieved. A rapid increase in plasma estradiol concentrations equivalent to estradiol levels reached in the second trimester of pregnancy and therefore inducing an additional strain on the hypothalamic–pituitary–thyroid axis. This marked change in estradiol levels may be responsible for TSH changes in the period immediately after the ART procedure.
Other possible risk factors that might be involved in the mechanism of TSH increase during OS include type of ovarian stimulation protocol selected, cause of infertility, ovarian reserve, history of previous IVF, number of oocytes retrieved and pregnancy achievement, however, no significant correlation was found with change of TSH in this study.