Context: Postnatal pituitary-testicular activation in infant boys is well characterized. However, the ovarian response to pituitary activation in infancy is less well understood.
Objective: The aim of the study was to compare postnatal developmental changes in the pituitary-ovarian axis in preterm and term infant girls.
Participants and design: Sixty-three infant girls, divided into three groups according to gestational age (GA) [i.e. full term (FT; n = 29; GA, 37-42 wk), near term (NT; n = 17; GA, 34-37 wk), and preterm (PT; n = 17; GA, 24-34 wk)] were examined monthly from 1 wk (D7) to 6 months (M1-M6) of age and reexamined at the corrected age of 14 months (cM14).
Main outcome measures: We performed a longitudinal follow-up of urinary FSH and serum anti-Müllerian hormone (AMH) levels and the number of follicles in transabdominal ovarian ultrasonography.
Results: The postnatal FSH surge was stronger and more prolonged in NT and PT girls than in FT girls (P ≤ 0.001). Increased folliculogenesis and a rise in AMH levels were observed in all three groups after the FSH surge. In NT and PT girls, follicular development was delayed in comparison with FT girls, and a decrease in high FSH levels around the 40th postmenstrual week was temporally associated with the appearance of antral follicles in ultrasonography and an increase in AMH levels.
Conclusions: The postnatal FSH surge results in transient ovarian stimulation in term and preterm girls. A delay in ovarian folliculogenesis shown in ovarian ultrasonography and by low serum AMH levels may provide an explanation for the exaggerated FSH surge in NT and PT girls.