Prolactin, fatherhood, and reproductive behavior in human males

Abstract

Although humans are considered unusual among mammals for the intensity of care that fathers often provide offspring, little is known about the hormonal architecture regulating human paternal investment. Prolactin has important reproductive functions in both female and male mammals and other taxa, making it a candidate regulator of human paternal behavior. Notably, prolactin is higher during periods of offspring care in some species, but it is unknown if this pattern occurs in human fathers. We draw on a sample of men (n = 289; age 21-23 at baseline) from Metropolitan Cebu City, Philippines to evaluate relationships between prolactin, assayed from dried blood spots, and components of reproductive behavior and relationship status. In this sample, fathers had higher prolactin than nonfathers (P = 0.006), and fathers of infants had borderline higher prolactin than fathers of older children (P = 0.054). Among single nonfathers at baseline (2005), baseline prolactin did not predict who transitioned to fatherhood by follow-up 4.5 years later. Among nonfathers, men with greater prolactin reported more lifetime sexual partners (P = 0.050) as well as more sexual activity in the month before sampling (P = 0.060). Our results suggest that fathers in Cebu have higher prolactin than nonfathers, with hormone levels highest among fathers of young infants. Although these findings are generally consistent with evidence from other species for pronurturing effects of prolactin, evidence for positive relationships between the hormone and measures of sexual behavior at Cebu point to likely complexities in the hormone's involvement in male reproductive strategy.

Mutual influences between partners’ hormones shape conflict dialog and relationship duration at the initiation of romantic love

“…PRL reduces hypothalamic-pituitary-adrenal (HPA) activity and was found to have antistress effects in rats (Donner, Bredewold, Maloumby, & Neumann, 2007;Schlein, Zarrow, & Denenberg, 1974;Torner, Toschi, Pohlinger, Landgraf, & Neumann, 2001). In addition, PRL appears to be involved in human fatherhood (Gettler, McDade, Feranil, & Kuzawa, 2012;Gordon et al, 2010b), and lower levels of PRL were found in fathers compared to nonfathers, which further decline after father-infant interaction (Gettler et al, 2011). Yet, while two studies showed correlations between PRL and depression following spouse loss (Jacobs et al, 1986;Lane et al, 1987), no study examined PRL in romantic attachment in humans.…”

Primate paternal care: Interactions between biology and social experience

“…Fathers with higher prolactin concentrations were more responsive to infant cries (Fleming et al, 2002) and they spent more time engaged in coordinated play with their infants than other men (Gordon et al, 2010b). Prolactin concentrations are higher in fathers than non-fathers in a sample of highly paternal men in the Philippines (Gettler et al, 2012a), whereas Grey (2007) found no difference in prolactin concentrations between residential and non-residential Jamaican fathers.…”

Hypothalamic Control of Prolactin Secretion, and the Multiple Reproductive Functions of Prolactin

“…763,764 Whilst numerous studies in a range of species, including humans, 765,766 have found an association between prolactin and paternal care, 767 the role that prolactin plays in the induction of paternal behavior is unclear and controversial, even in rodents. 763,764 Whilst numerous studies in a range of species, including humans, 765,766 have found an association between prolactin and paternal care, 767 the role that prolactin plays in the induction of paternal behavior is unclear and controversial, even in rodents.…”