During the course of days, the women registered menses and ovulation, while the men registered sexual activity, physical exercise, alcohol intake and illness (confounders), and obtained daily saliva samples for testosterone measurements. Gender-affirming hormone therapy (GAHT), also referred to as hormone replacement therapy (HRT), can impact menstrual periods and cycles overall. Men also have about 10 times more testosterone than women, so their hormone cycle is usually all about how their testosterone affects them. While the female menstrual cycle varies between individuals, this is typically what happens to testosterone and estrogen . Research by the Journal of Clinical Endocrinology and Metabolism suggests that from day eight until ovulation, both testosterone and estrogen levels rise . Yes, testosterone is higher during the menstrual cycle, especially in the mid-phase. Some people who start testosterone stop having periods – this change depends on how much testosterone you inject or apply (if you are on T gel), and how your body responds to it.
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH), released from the pituitary gland, are the hormones responsible for stimulating ovarian egg development, and ovulation. Some people experience regular bleeding or spotting even after years of using testosterone. However, just under 1 in 4 people (25%) report that it takes longer than six months for their period to stop.
The serum total testosterone (TT) level exhibits a circadian rhythm, with the highest observed in the early morning and the  lowest in the late evening 16, 17. Testosterone is then transported to the preovulatory granulosa cells, where it is aromatized to estrone and estradiol by 17-β-hydroxysteroid dehydrogenase type I, stimulated by Follicle stimulating hormone (FSH) . After puberty, increased peripheral conversion and increased production leads to higher T levels 9, 10.
While slight fluctuations of testosterone are normal throughout life, persistently abnormal levels can have serious repercussions on a woman's health, including her menstruation. Since all three hormones are interlinked, an imbalance of one can throw off the others, compromising the health of the female reproductive system and menstrual patterns. Moreover, normal testosterone levels are necessary for maintaining estrogen and progesterone balance. Once produced, some of testosterone in the female body is converted into estrogen.1
"Women with low body fat often do not produce sufficient amounts of sex hormones. These testosterone fluctuations are perfectly normal and play a key role in fertility, sex drive, and even mental health. It's crucial to understand these hormonal changes, as they play a significant role in women's health.