How do your hormone levels change throughout your menstrual cycle?
Your hormone levels follow a recognisable pattern throughout the cycle: oestrogen and progesterone rise and fall at set moments, with a sharp LH peak around ovulation. Bear in mind that there are large differences between women, and that the pill largely suppresses this pattern.
The most pronounced hormonal movements are those of oestrogen, LH and FSH. In the first half of the cycle (the follicular phase, from menstruation to ovulation) oestrogen rises steadily, while LH and FSH are still low. Just before ovulation, both undergo a sharp peak: these are the trigger signals that induce ovulation, after which oestrogen briefly dips.
After ovulation, progesterone takes centre stage. In this second half of the cycle (the luteal phase) both progesterone and oestrogen rise again, with progesterone as the dominant hormone. Towards the end of the luteal phase, both drop off quickly, which triggers menstruation. It is precisely this fall in oestrogen just before menstruation that appears to trigger menstrual migraine: oestrogen influences pain sensitivity in the brain, and it is the fluctuations that matter, not a persistently high or low level.
Around ovulation, androgens (testosterone and DHEA) are also slightly elevated compared to the menstruation period. In the premenstrual phase they fall again. These are small shifts. Prolactin does fluctuate throughout the cycle, but follows no recognisable pattern and appears to be independent of the other hormonal movements. DHEA-S, an adrenal hormone, shows no cyclical change at all.
Despite all these fluctuations, no measurable differences in athletic performance, sleep or recovery between cycle phases were found in trained women. This is partly because hormone levels can vary considerably between women and even within each phase. Women who use the combined contraceptive pill see these fluctuations largely disappear: their oestrogen, progesterone and testosterone remain virtually stable throughout the entire pill cycle.
Smoking is associated with disrupted hormone levels during the cycle: both active and passive smoking were in eight studies linked to higher oestradiol and LH levels and elevated progesterone values later in the cycle. This is an association, not a proven cause, and the shifts are not always in the same direction. Nevertheless, it is a reason for caution, especially for women who already experience hormone-related complaints.
This answer is based on two extensive literature reviews and several smaller studies in humans. The patterns of oestrogen, progesterone, LH and FSH are consistent and well documented. The androgens and adipokines are less thoroughly mapped; the researchers themselves point to large variation in hormone levels within each phase (coefficients of variation of 28 to 95%), which makes firm statements about individuals difficult. The evidence on smoking and hormones is limited and not fully consistent in the direction of the disruptions.
What hormone levels are associated with polycystic ovary syndrome (PCOS)?
In PCOS, elevated androgens, a higher LH/FSH ratio and greater insulin resistance are the most reliable hormonal features. If you suspect you have PCOS, these are the values your general practitioner or gynaecologist will measure first.
What exactly is brain fog and where does it come from?
Brain fog most likely has multiple simultaneous causes, of which a leaking blood-brain barrier in long COVID is the best substantiated. Exactly what goes wrong in the brain differs depending on the underlying condition, so the approach also varies by situation.