Minipuberty in Daughters of Women with Hypothyroidism during Pregnancy

Minipuberty is a term describing transient postnatal activation of the hypothalamic-pituitary-gonadal axis, likely playing an important role in the postnatal growth of female genital organs and breasts. Unlike infant boys, there are no data concerning the impact of gestational hypothyroidism on the course of minipuberty in infant girls. Therefore, the aim of the current study was to investigate the reproductive axis and genital organs in daughters of women with thyroid hypofunction during pregnancy. The study population included three matched groups of infant girls: offspring of women with thyroid hypofunction non-substituted or inadequately treated during gestation (group 1), descendants of women adequately substituted throughout pregnancy (group 2), and daughters of healthy women (group 3). Salivary concentrations of estradiol, progesterone, 17-hydroxyprogesterone, and androgens (testosterone, androstenedione, and dehydroepiandrosterone sulfate) and urine levels of gonadotropins were measured monthly from month 1 to month 6, once every two months between postnatal months 6 and 12, and once every three months between postnatal months 12 and 18. During each visit, we also determined ovarian volume, uterine length, and breast diameter. Concentrations of FSH, LH, and estradiol were lowest in group 1, and this group was also characterized by the shortest detection period for gonadotropins and estradiol. These differences were paralleled by differences in ovarian volume, uterine length, and breast diameter. There were no differences between groups 2 and 3 in levels of both hormones and in the size of the measured structures. The obtained results seem to indicate that non-substituted or inadequately substituted hypothyroidism during pregnancy may impair the course of minipuberty in the female offspring.