Fatherhood & Health:

Fatherhood - Evolution and Human Paternal Behavior
P B Gray & K G Anderson; 2012

Fatherhood appears to have both protective and deleterious impacts on men's health. The parenting of young children tends to negatively impact marital quality, meaning that men lose some of the beneficial effects of affiliative pair-bonds. Male mental health may suffer, especially if his partner is also struggling with mental health difficulties. Sleep and sexual challenges may exacerbate these difficulties. Young children, particularly those in daycare, can also serve as disease vectors (for example, Hillis et al. 1992), presenting a father with greater exposure to transmissible diseases. The outcome of these types of issues is that fathers of young children may have compromised health.

Yet as those children age, men's health may rebound. The strains of caring for young children wane. Those children may provide social and material support to aging parents. Perhaps an older father, living somewhere without a Social Security check to cash, is supported partly by the sons or daughters he raised to adulthood. Put all of these health and fatherhood variables together, and maybe observations like the following make sense. As shown in a U.S. study of approximately five thousand adults, the effects of fatherhood altered across a man's life and his children's ages (see E. E. Bartlett 2004). In this large U.S. study, among married men aged forty years or younger, 8.9% of fathers but only 1.1% of married men without children rated their health as fair or poor. In the same study, among married men aged forty-one to sixty-four, 16.5% of married fathers with children but 22.7% of married men without children rated their health as fair or poor. Similarly, in an Australian study, fathers of preschool-aged children reported worse health than fathers did of older children (Hewitt, Baxter, and Western 2006). These data suggests that earlier in life fatherhood may be a drain on a man's health, but that same relationship may have later, beneficial effects. This pattern appears to be the overarching perspective on fatherhood and health.

[This excerpt doesn't seem to be based on very hard data, but I think it makes some interesting points.]

Do testosterone declines during the transition to marriage and fatherhood relate to men's sexual behavior? Evidence from the Philippines

Do testosterone declines during the transition to marriage and fatherhood relate to men's sexual behavior? Evidence from the Philippines
Lee T Gettler et al.; November 2013
Hormones and Behavior


Abstract

Testosterone (T) is thought to help facilitate trade-offs between mating and parenting in humans. Across diverse cultural settings married men and fathers have lower T than other men and couples' sexual activity often declines during the first years of marriage and after having children. It is unknown whether these behavioral and hormonal changes are related. Here we use longitudinal data from a large study in the Philippines (n = 433) to test this model. We show that among unmarried non-fathers at baseline (n = 153; age: 21.5 ± 0.3 years) who became newly married new fathers by follow-up (4.5 years later), those who experienced less pronounced longitudinal declines in T reported more frequent intercourse with their partners at follow-up (p < 0.01) compared to men with larger declines in T. Controlling for duration of marriage, findings were similar for men transitioning from unmarried to married (without children) (p < 0.05). Men who remained unmarried and childless throughout the study period did not show similar T-sexual activity outcomes. Among newly married new fathers, subjects who had frequent intercourse both before and after the transition to married fatherhood had more modest declines in T compared to peers who had less frequent sex (p < 0.001). Our findings are generally consistent with theoretical expectations and cross-species empirical observations regarding the role of T in male life history trade-offs, particularly in species with bi-parental care, and add to evidence that T and sexual activity have bidirectional relationships in human males.

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Conclusion

In sum, we found that newly married new fathers who experienced greater declines in T also reported less frequent sexual intercourse with their partners at follow-up, 4.5 years later. We also showed that men who engaged in frequent sexual activity both before and after becoming married fathers experienced milder declines in T compared to less sexually active men, which suggests that sexual behavior could also have long-term implications for T production. This finding is consistent with the increasingly recognized observation that relationships between hormones and social behavior are likely reciprocal, rather than uni-directional. To our knowledge, these results are the first longitudinal evidence relating marriage/fatherhood-driven T decreases to men's sexual behavior.

Evolution of Fatherhood

Evolution of Fatherhood (Family Relationships: An Evolutionary Perspective)
David C Geary; 2007
http://web.missouri.edu/~gearyd/files/Geary%20[2007%20Evo%20of%20Fatherhood%20proof].pdf

Conclusion:

>Cultural debates regarding men’s contributions to families and their children and the occasional rancor over the unequal contributions of men and women to parenting belie a deeper and rarely considered scientific riddle; specifically, on the basis of little or no male parenting in nearly all other mammalian species and among our two closest living relatives, it is a scientific curiosity that men invest in families and children at all. To understand how men’s parenting evolved and how it is maintained in the here and now, we must consider the factors related to the evolution and expression of male parenting across other species. These factors involve tradeoffs that balance the benefits of male protection and provisioning to the health and later competitiveness of his offspring, weighed against the risk of cuckoldry and the cost of lost mating opportunities. Of course, it is likely that male parenting would benefit offspring even in species where this parenting does not occur. However, in these species, males that compete for access to mates out-reproduce any parental fathers, and thus any tendency toward the latter does not evolve.
Men’s parenting is consistent with the same cost–benefit tradeoffs in other species in which paternal investment is found. In traditional and developing societies today and in the historical record, men’s investment in families substantively reduced children’s morality risks and improved their physical health and development. In these societies and in Western societies today, men’s investment often facilitates their children’s ability to acquire the skills needed to compete in adulthood. Children who become successful adults are able to better care for and thus lower the mortality risks and enhance the later competitiveness of men’s grandchildren. Men also benefit because of comparatively high levels of paternity certainty, although cuckoldry does occur and men and women show evidence of corresponding adaptations. Women’s reluctance to engage in casual sex greatly reduces men’s mating opportunities, and in so doing, lowers the opportunity cost of paternal investment.
Even with an evolved bias to invest in children, there is considerable variation among men as to when and with whom they will invest in a family. The influences on the expression of men’s parental behaviors are multifaceted and range from the genes that influence the expression of parentingrelated hormones to the quality of the marital relationships to cultural mores regarding marriage practices (e.g., whether or not polygyny is allowed). A comparative and evolutionary perspective on men’s parenting provides a broader perspective for understanding these patterns and allows us to more fully understand when, where, and with whom men will invest in families.<