Impact of Maternal Euthyroid Autoimmune Thyroiditis on Minipuberty in Female Offspring

Minipuberty is a transient activation of the hypothalamic-pituitary-gonadal axis in infancy that contributes to the postnatal development of sexual organs. Its course has been shown to be influenced by maternal hypothyroidism. This study aimed to evaluate the reproductive axis and genital development in infant girls born to women with euthyroid autoimmune thyroiditis.

The study involved three groups of infants: two groups were daughters of euthyroid women with autoimmune thyroiditis, while the third group (control) consisted of daughters of women without thyroid disease during pregnancy. Half of the mothers with thyroiditis received additional vitamin D and selenium supplementation during pregnancy, whereas the other half did not. During the first 18 months of life, periodic assessments were conducted of gonadotropin concentrations in urine, as well as salivary levels of estradiol, progesterone, testosterone, androstenedione, and DHEA-S. Additionally, ovarian volume, uterine length, and breast diameter were measured in the infants.

Daughters of women with autoimmune thyroiditis who did not receive supplementation during pregnancy exhibited lower levels of LH, estradiol, and progesterone, as well as a more rapid decline in LH and estradiol to below detectable levels, compared with daughters of healthy women. These hormonal differences were accompanied by smaller uterine length and breast diameter in this group. No differences were observed between the offspring of non-supplemented women with thyroiditis and daughters of healthy women regarding the levels of other hormones or ovarian volume. The dynamics of all assessed hormone levels and organ measurements did not differ between daughters of euthyroid women with thyroiditis who received vitamin D and selenium supplementation and daughters of healthy women. LH and progesterone levels showed inverse correlations with anti-thyroid peroxidase antibody titers, whereas uterine and breast dimensions positively correlated with estradiol levels.

These findings suggest that maternal euthyroid autoimmune thyroiditis can affect the progression of female minipuberty, while supplementation with vitamin D and selenium during pregnancy may mitigate this effect.