Testosterone levels drop in men with pregnant partners

During pregnancy, expectant fathers experience a variety of hormonal and physiological changes. One of the most significant changes that occur in expectant fathers is a drop in testosterone levels.

Testosterone is an important hormone that plays a role in various bodily functions, including the development of male sexual characteristics, muscle growth, and bone density. Testosterone levels are typically highest in men in their 20s and gradually decline with age. However, during pregnancy, expectant fathers experience a temporary drop in testosterone levels.

The exact mechanism behind this drop in testosterone levels in men with pregnant partners is not fully understood, but it is thought to be related to hormonal changes that occur during pregnancy. Some studies have suggested that the drop in testosterone levels may be related to changes in levels of other hormones, such as cortisol and prolactin.

One study published in Hormones and Behaviour investigated changes in testosterone levels in expectant fathers. The study included 34 men who were expecting their first child and measured their testosterone levels before and after their partner's pregnancy. The results showed that expectant fathers experienced a significant drop in testosterone levels, with the largest drop occurring in the third trimester of pregnancy.1

While the reasons for the drop in testosterone levels in expectant fathers are not fully understood, there may be some potential implications for fathers and their offspring. Some studies have suggested that lower testosterone levels in fathers may be associated with increased paternal investment and caregiving behavior. Other studies have suggested that lower testosterone levels in fathers may be associated with improved cognitive and behavioural outcomes in their children.

One study published in the Proceedings of the National Academy of Sciences investigated the association between paternal testosterone levels and cognitive outcomes in children. The study included 157 children and measured their cognitive abilities at age 1 and age 2. The results showed that children of fathers with lower testosterone levels had better cognitive outcomes than children of fathers with higher testosterone levels.2

The reasons for this drop are not fully understood but may be related to hormonal changes that occur during pregnancy. While there may be some potential implications for fathers and their offspring, further research is needed to fully understand the effects of the drop in testosterone levels in expectant fathers.

References:

1. Storey AE, Walsh CJ, Quinton RL, Wynne-Edwards KE. Hormonal correlates of paternal responsiveness in new and expectant fathers. Evol Hum Behav. 2000;21(2):79-95. doi:10.1016/s1090-5138(99)00042-4
2. Gettler LT, McDade TW, Agustin SS, Feranil AB, Kuzawa CW. Longitudinal evidence that fatherhood decreases testosterone in human males. Proc Natl Acad Sci USA. 2011;108(39):16194-16199. doi:10.1073/pnas.1105403108

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