Men who produce more testosterone are more likely to engage in extramarital sex. Men who produce less testosterone are more likely to be in a relationship or married, and men who produce more testosterone are more likely to divorce. However, the testosterone changes observed do not seem to be maintained as relationships develop over time.
Because of this sharp suppression, injections often have one of the strongest and quickest effects on sperm count. While every type of TRT can lower sperm production, the speed, degree, and pattern of this effect can vary. Because fertility preservation involves hormone-based medicine, it must be supervised by a qualified healthcare professional. There are several medical options doctors use to help protect fertility while someone is taking testosterone or treating low testosterone. When LH and FSH drop, sperm production slows down or stops.
These conditions may interfere with the HPG axis, making natural testosterone and sperm production harder to regenerate. Even if a blood test shows strong "T levels," the actual testosterone inside the testicles may become too low to support sperm development. For healthy sperm to grow, intratesticular testosterone needs to be much higher than the testosterone circulating in the blood—often 50–100 times higher.
Like other androsteroids, testosterone is manufactured industrially from microbial fermentation of plant cholesterol (e.g., from soybean oil). This also made it obvious that additional modifications on the synthesized testosterone could be made, i.e., esterification and alkylation. These independent partial syntheses of testosterone from a cholesterol base earned both Butenandt and Ruzicka the joint 1939 Nobel Prize in Chemistry.
These hormones are part of the hypothalamic-pituitary-gonadal (HPG) axis, which regulates both testosterone production and sperm production. This system makes sure the body produces the right amount of hormones to support both sexual health and fertility. When the brain senses that the body needs more testosterone or more sperm, it sends out signals in the form of hormones. Unlike external testosterone therapy, which can suppress natural sperm production, hCG maintains or even improves sperm count.