Progesterone Levels in Perimenopause: What to Know and Expect
Learn how progesterone levels change during perimenopause, what low progesterone feels like, how to test it, and what your results mean.
What Progesterone Does in Your Body
Progesterone is a hormone produced mainly by the corpus luteum after ovulation. It prepares the uterine lining for a potential pregnancy and plays a calming role in the nervous system. It also supports sleep, bone density, and mood regulation. When ovulation becomes infrequent or stops, progesterone production drops significantly. This is one of the first hormonal shifts that defines perimenopause.
Why Progesterone Drops Early in Perimenopause
Unlike oestrogen, which fluctuates up and down for years, progesterone tends to decline steadily as ovulation becomes less reliable. You can still have a period without ovulating, in which case no progesterone is produced that cycle. Over time, fewer ovulatory cycles means chronically low progesterone. This relative deficiency, even when oestrogen is still present, drives many early perimenopause symptoms.
Symptoms Linked to Low Progesterone
Low progesterone is associated with poor sleep, particularly difficulty staying asleep in the second half of the night. Anxiety and a sense of being mentally wired but physically tired are also common. Heavy or irregular periods often reflect low progesterone relative to oestrogen. Some women describe a general feeling of being off balance or emotionally reactive in ways that feel unlike their usual selves.
How Progesterone Is Tested
A serum progesterone test is most informative when taken around seven days after expected ovulation, typically day 21 of a 28-day cycle. This is called a day 21 progesterone test. If your cycles are irregular, the timing becomes harder to pin down. Your GP can advise on when to test. The result tells you whether you ovulated in that cycle and how much progesterone was produced.
What Your Results Mean
A level above 16 to 30 nmol/L in the mid-luteal phase suggests ovulation occurred. Levels below 10 nmol/L suggest poor ovulation or anovulation. In perimenopause it is common to see low or undetectable mid-luteal progesterone even when periods continue. This confirms that cycles are becoming less reliably ovulatory, which explains sleep disruption and mood changes even when periods seem normal.
Options if Your Progesterone Is Low
Your doctor may discuss progesterone replacement as part of HRT, or prescribe body-identical micronised progesterone, which also has the benefit of improving sleep when taken at night. Lifestyle factors such as stress reduction, adequate nutrition, and avoiding over-exercise can support progesterone production in earlier perimenopause. Tracking your sleep and mood patterns gives you useful data to share with your doctor when discussing next steps.
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