ESPE Yearbook of Paediatric Endocrinology

J Clin Endocrinol Metab. 2022;107(7):1965-75. doi: 10.1210/clinem/dgac173.PubMed ID: 35323957

Brief summary: This population-based birth cohort study related infancy serum testosterone concentrations at age 3 months to parameters of reproductive function at age 18 to 20 years in 259 males. Serum testosterone in infancy predicted adult total sperm counts, and other reproductive hormones and genital measures showed good correlations between infancy and adulthood.

The ‘minipuberty’ of infancy is well recognised by Paediatric Endocrinologists as a window of endogenous sex hormone activity, during which we can very usefully investigate patients with suspected hypothalamo-pituitary or gonadal disorders. However, beyond our professional community, the existence of this phenomenon is surprising and, even to us, the physiological role of this process is largely unknown.

These authors are leading researchers in reproductive biology and clinical reproductive disorders, and they set up the Copenhagen Mother-Child cohort to first characterise the physiological changes of infant minipuberty. This long-term follow-up of the cohort provides unique and powerful data showing the remarkable correlations between infancy and adult reproductive function. Median (IQR) total sperm counts ranged from 84 (54-138) million spermatozoa for boys in with the lowest infancy testosterone tertile, to 193 (56-287) million spermatozoa in the highest tertile. Infant-adult correlations in sex hormone levels were highest for FSH, and lower but significant for inhibin B, SHBG, penile length, and testis volume. Another recent paper by this group showed that male minipuberty shows a surprising temporal dissociation of Leydig and Sertoli cell activity, which peak at ages 1 month and 4-5 months, respectively (1). Normal reference data are provided for reproductive hormones concentrations in male infants.

The current findings suggest that a boy’s reproductive set-point is apparent shortly after birth and persists to adult life. While this provides a valuable early life window into our patients’ later reproductive potential, an important question is whether these links reflect inherent (e.g. genetic) set-points, or whether later reproductive function might also be programmed by disruption and/or therapeutic early hormone replacement interventions?

Reference: 1. Busch AS, et al. Dynamic Changes of Reproductive Hormones in Male Minipuberty: Temporal Dissociation of Leydig and Sertoli Cell Activity. The Journal of Clinical Endocrinology & Metabolism, Volume 107, Issue 6, June 2022, Pages 1560–1568, https://doi.org/10.1210/clinem/dgac115.