Ovulation, and Why Irregular Periods Are Trying to Tell You Something
Think of your brain as the conductor of an orchestra, and your ovaries as the musicians. Most of the time we focus entirely on the musicians, are the ovaries working, is there an egg. But the conductor matters just as much, and it's often the conductor that's out of rhythm.
At the base of your brain, a tiny cluster of cells sends out a hormone called GnRH, not as a steady stream but in pulses, a bit like Morse code. The speed and strength of those pulses changes depending on what's going on in your life, your calorie intake, your stress levels, whether your body senses safety or threat. Those pulses tell your pituitary gland when to release two other hormones, FSH and LH, which in turn tell your ovaries what to do.
In the first half of a normal cycle, those pulses are steady and moderate, encouraging a group of follicles to start developing. As one follicle takes the lead and starts producing more oestrogen, the pulses speed up, until oestrogen peaks and triggers a surge of LH. That surge is what causes ovulation. After that, progesterone rises and tells the brain to slow the pulses right back down again, resetting things for the next cycle.
When this rhythm gets disrupted, and it disrupts fairly easily, you end up with irregular ovulation or none at all. A few of the more common patterns:
If the pulses slow down too much, often from chronic stress, very low calorie or very low carbohydrate eating, or overtraining, you can stop ovulating altogether. This is called hypothalamic amenorrhoea, and it's essentially your brain deciding this isn't a safe time to reproduce. It's worth knowing that under eating, including cutting carbohydrates hard, is one of the most common and most overlooked triggers. It also affects your thyroid, so the two often show up together.
If the pulses stay fast and don't slow down properly after ovulation, or ovulation doesn't happen at all, LH can end up running higher than FSH. This pushes the ovaries toward producing more androgens rather than maturing an egg cleanly, which is part of the picture in PCOS type presentations.
And if a hormone called prolactin is running high, it directly suppresses those GnRH pulses. This can come from an underactive thyroid, certain medications, high stress, or occasionally a small and usually benign pituitary growth. Raised prolactin on more than one test is always worth raising with your GP.
The useful diagnostic clue here is actually quite simple. In your reproductive years, LH and FSH should sit roughly level with each other. If LH is low, that points toward the hypothalamic, stress driven pattern. If both are high, that can point toward perimenopause. If LH is notably higher than FSH in a younger woman, that's more suggestive of a PCOS type pattern.
None of this is something you need to diagnose yourself from a blood test. But understanding that irregular ovulation almost always has a "why" behind it, rather than being random bad luck, changes how you approach fixing it. Chasing a supplement without addressing the underlying driver, whether that's stress, under fuelling, or thyroid function, tends to be a losing game.
Worth knowing before your next cycle:
Ovulation isn't just about getting pregnant, it's what produces progesterone, and progesterone is what protects your mood, bones and sleep in the second half of your cycle
A tiny rise in temperature after ovulation isn't the same as a proper progesterone response
Under 40 with no period for six months and consistently high FSH warrants investigation, not a wait and see approach
If your cycle has felt like a mystery, or you've been told everything's "normal" when it doesn't feel that way, I'd love to help you work out what's actually going on.