Maternal Cortisol and Paternal Testosterone Correlated with Infant Growth via Mini Puberty

Objectives

Infant testosterone (T) surges early in life. This period (known as mini puberty) is crucial to development. Little is known as to what the ultimate function of mini puberty might be. We predicted that parents with putative endocrine signatures of challenging environments (elevated levels of maternal cortisol and paternal T) may be related to elevated levels of infant T. In turn, these endocrine relationships are hypothesized to influence infant growth.

Methods

In a U.S. sample (n = 225 families) of first-time parents and their infants, we measured infant length and weight at three occasions—birth, 3 months old, and 10 months old. We conducted salivary assays of infants for T, mothers for cortisol, and paternal T during the early postnatal period.

Results

We utilized latent growth curve modeling to explore changes in length and weight as predicted by infant T. Infant T predicted the slope of length gains across the study period. Maternal cortisol and paternal T (positively correlated with one another) were positively related to infant T. Neither maternal cortisol nor paternal T predicted the slope of length gains. In an exploratory model, temperament was not related to neuroendocrine measures. Gains in weight—unlike length—were not related to infant T.

Conclusions

The ultimate function of mini puberty in infant growth is nuanced. In addition—at a time of rapid hormone changes across mothers, fathers, and infants—our results suggest that a tripartite neuroendocrine relationship is conceivable. Discussion surrounds the potential role of mini puberty and the numerous limitations of the study.