Background: The transient postnatal activation of the hypothalamic-pituitary-gonadal (HPG) axis, also called minipuberty, is a phenomenon during which gonadal hormone levels increase up to adult levels.
Results: In boys gonadotropin and testosterone levels peak at one moths of age and are significantly higher in preterm than in full-term boys. Simultaneously, there is penile growth and the levels of prostate specific antigen increase, indicating increase in androgen effects. In preterm girls, FSH levels are extremely high after birth, but they decrease to similar levels as in full-term girls around the term age. Interestingly, when gonadotropin levels are assessed against postmenstrual age (i.e., age from the last menstruation of the mother) rather than chronological age (i.e., time from birth) the gonadotropin levels in premature infants actually decline to similar levels as in full-term infants at the same developmental stage suggesting that the duration of minipuberty is developmentally regulated. In girls, the decrease in FSH from its peak is associated with the maturation of antral follicles and increase of the follicle-derived AMH levels. Estradiol levels are higher in girls than in boys, but in girls the levels vary and do not display a similar uniform peak at one month as male testosterone levels. The growth of estrogen responsive target tissues (i.e., mammary glands and uterus) are maximally stimulated in full-term girls at birth by the high intrauterine estrogen whereas in preterm girls, the growth of the mammary glands and the uterus are positively correlated with estradiol levels.
Conclusion: The possible long-term significance of the observed differences in minipuberty between full-term and preterm infants requires further studies. These should include effects on reproductive development, childhood growth, bone mineralization, childhood psychosexual development, timing of puberty, sexual behaviour, and reproductive capacity in adulthood.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology