A menstrual cycle hormone chart, explained

How estrogen, progesterone, LH and FSH rise and fall over one cycle, what drives each change, and how to read any hormone chart, Bloom’s included.

Last reviewed 22 October 2026Checked against the sources listed below

This guide is for anyone who has seen a menstrual cycle hormone chart, with its crossing curves, and wants to know what it is actually showing: which hormone does what, what makes each one rise and fall, and why your own cycle may not look like the drawing.

An idealised hormone chart

This is a drawing of a textbook 28-day cycle, not a measurement. Each hormone is drawn on its own scale, so the heights of the curves can’t be compared with each other; what matters is when each one rises and falls. Day 1 is the first day of your period, and the cycle runs to the day before the next one starts.^[1]

Estrogen: the first half

Estrogen is the hormone of the follicular phase. While follicles in an ovary grow, rising estrogen rebuilds and thickens the lining of the uterus.^[2] Its rise is also what sets off ovulation: estrogen from the ovary acts on the brain and triggers the surge of luteinizing hormone (LH) that releases the egg.^[3]

After ovulation, estrogen usually rises a second time, to a smaller peak in the middle of the luteal phase, though some cycles don’t show that second peak at all.^[4] The corpus luteum, which forms after ovulation, makes some estrogen alongside its progesterone.^[5]

LH and FSH: the signals from the brain

Two hormones from the pituitary gland drive the ovary. The hypothalamus releases gonadotropin-releasing hormone, which makes the pituitary release follicle-stimulating hormone (FSH) and LH.^[6] In the first half, FSH causes follicles to mature, which in a textbook cycle happens between about days 6 and 14.^[6]

LH is best known for one moment. Around day 14 of a textbook cycle, a sudden surge of LH makes the ovary release a mature egg.^[6] That surge is what home ovulation tests look for in urine, and MedlinePlus says a positive result means ovulation is likely within the next 24 to 36 hours, though not for everyone.^[7] Irregular cycles can make the surge harder to catch.^[7]

Progesterone: the second half

Progesterone is the hormone of the second half. Once the egg is released, the follicle it came from turns into the corpus luteum, and the corpus luteum makes progesterone.^[5] Progesterone thickens the lining of the uterus so it is ready in case a pregnancy begins.^[5] It also holds back the release of LH and FSH.^[3]

The middle of the luteal phase is when progesterone stays at its highest.^[4] That is why a chart’s second half looks so different from its first: estrogen leads before ovulation, and progesterone leads after it.

What makes the hormones fall

If no egg is fertilized, the high progesterone slows the release of LH, and progesterone and estrogen then drop quickly at the end of the cycle.^[3] As they fall, the lining of the uterus is shed, and that is your period.^[2] The low point on the left of the chart is the same moment as the drop on the right: one cycle ending and the next beginning.

If a pregnancy does begin, the fertilized egg releases human chorionic gonadotropin (hCG), which keeps the corpus luteum making progesterone.^[3] In that case the curves on a cycle chart simply stop applying.

Why your own chart would look different

• Your cycle probably isn’t 28 days. The Office on Women’s Health puts the normal range at 24 to 38 days.^[1] Most of that difference sits in the follicular phase, while the luteal phase changes much less,^[8] so in a longer cycle the estrogen climb and the LH surge come later, and the progesterone hump keeps roughly its shape.
• Not every cycle has ovulation. Irregular cycles can be anovulatory, meaning no egg is released.^[9] Without ovulation there is no corpus luteum, so the progesterone rise on the right of the chart doesn’t happen.
• Peaks vary. The second estrogen peak is missing in some cycles,^[4] and the exact heights differ from person to person and month to month.

Hormone charts in Bloom

Bloom includes hormone charts like this one for each mode. In cycle mode they show estrogen, progesterone and testosterone; in pregnancy mode, hCG, progesterone, estrogen and relaxin; and in postpartum mode, estrogen, progesterone, prolactin and oxytocin. They are educational curves that show the typical pattern, not your own levels, because Bloom can’t measure hormones.

Bloom can’t confirm ovulation either. If you log ovulation tests, it treats a positive one as a sign to help place your phases, not as proof, and it is not a fertility tool or contraception. To see how Bloom works out which phase you are in, read the cycle phase tracker page; for what happens in your body in each phase, see the four phases of the menstrual cycle.

Reading any hormone chart

• Check whether it is idealised. Most charts online are drawings of a textbook cycle. They show a shape, not numbers you should expect.
• Check the scale. If hormones share an axis, the heights may be meaningful; if each has its own, only the timing is.
• Line it up with your own dates. Count from day 1 of your period, and stretch or shrink the first half to fit your usual cycle length.
• Remember what it can’t tell you. Knowing the typical shape doesn’t tell you your own levels. That needs a blood test, which a doctor can arrange.

Bloom is a wellness and planning app. It is not a medical device, it does not diagnose or treat any condition, and it is not a method of contraception. This page is general information, not medical advice. If something about your cycle worries you, talk to a doctor, nurse or midwife.