Reproductive hormones: definition and meaning
Reproductive hormones are chemical messengers that control puberty, the menstrual cycle, fertility and pregnancy. In the cycle, the brain releases GnRH, FSH and LH, and the ovaries answer with estrogen and progesterone, plus small amounts of testosterone. They rise and fall in a feedback loop each month, and their changes affect mood, energy, sleep, skin and appetite.
The main players
| Hormone | Made in | Main job |
|---|---|---|
| GnRH | Hypothalamus | Starts the chain |
| FSH | Pituitary | Grows follicles |
| LH | Pituitary | Triggers ovulation |
| Estrogen | Ovaries (follicles) | Builds the lining, fertile mucus |
| Progesterone | Corpus luteum | Steadies the lining, raises temperature |
| Testosterone | Ovaries, adrenals | Libido, energy, muscle |
| hCG | Placenta | Keeps early pregnancy going |
How they work together
The hypothalamus, pituitary and ovaries form a loop called the HPO axis. Rising estrogen first holds FSH down, then at a peak flips to trigger the LH surge. After ovulation, progesterone and estrogen hold the brain signals low until the corpus luteum fades and the cycle restarts. Read the full guide: menstrual cycle hormones.
Hormones and mood
Estrogen and progesterone act on brain systems for mood, including serotonin and GABA. Most people's hormone levels are normal, but some brains are more sensitive to the changes, which is what drives PMS and PMDD. Thyroid hormones, prolactin and stress hormones also influence the cycle, which is why stress, illness or a thyroid problem can change your periods.
Frequently asked questions
Do hormones change every day?
Yes. Estrogen, progesterone, FSH and LH all shift day by day through the cycle, which is why the same week can feel different from the next.
Which hormone causes PMS?
No single hormone is abnormal. PMS seems to come from sensitivity to the normal drop in estrogen and progesterone after ovulation.
Can a blood test check all my hormones?
Hormone levels change daily through the cycle, so tests are timed to specific days and chosen for a specific question.
Sources
This page is for information only and isn’t medical advice. If something worries you, please talk to a doctor.
Keep reading
Menstrual cycle hormones: a simple chart of what rises and fallsMenstrual cycle hormones explained simply: how estrogen, progesterone, LH and FSH rise and fall through each phase, and how they shape mood and energy.Estrogen: definition and meaningEstrogen (oestrogen) is the hormone that builds the uterine lining and drives ovulation. How it rises and falls in your cycle and how it affects mood.
Progesterone: definition and meaningProgesterone is the hormone made after ovulation that prepares the uterus for pregnancy. Its role in the luteal phase, PMS, mood, sleep and temperature.Menstrual cycle: definition and meaningThe menstrual cycle is the monthly hormone cycle that prepares the body for pregnancy. Its four phases, normal length, and how it shapes mood.
Menstrual cycle mood: how you feel in each phase, and whyHow menstrual cycle mood changes through all four phases: what hormones do, why some people feel it more, and how to learn your own pattern.