U.S. men’s testosterone (T), partnering, and residence with children: Evidence from a nationally-representative cohort (NHANES) and relevance to clinically low T

Men who are in committed partnerships and fathers who are involved with caregiving often have lower testosterone than their peers. Most prior studies of human paternal psychobiology have focused on families with infants and young children, often with relatively small sample sizes. This has left a number of important questions relatively unresolved regarding how men's testosterone varies based on life history status (partnering and parenting) as they age and their family demographics change. Moreover, variation in testosterone based on partnering and parenting may have implications for men's health, including their likelihood of having clinically low testosterone. Here, we combined data from three waves of the National Health and Nutrition Examination Survey (NHANES) to address these questions in a large, U.S.-population representative sample (N = 4903). We stratified men according to whether they were partnered and living with younger (0-5 years old) versus older (6-17 years old) children, respectively. Using serum total testosterone data assayed via liquid chromatography tandem mass spectrometry, we found that partnered men had lower testosterone than single men not residing with children, regardless of whether partnered men resided with one or more young children. In contrast, partnered men residing with two or more older children had significantly lower testosterone than single men and partnered men who did not reside with children. We did not find that partnered men or those residing with children had increased risk of clinically low testosterone compared to single men not living with children. This suggests that variation in U.S. men's testosterone based on family characteristics does not significantly affect their risks for clinically low testosterone. Our results showing lower testosterone in partnered men living with older children suggest the possibility of fatherhood-related regulation of testosterone as families mature, which has received little attention.