Bleeding Changes in Perimenopause

One of the most unsettling things about perimenopause is how suddenly your periods can stop behaving like your usual periods. You may have spent decades knowing roughly when they would arrive, how long they would last and what your normal flow looked like. Then, seemingly out of nowhere, everything changes, the period comes days late, the next one arrives early, one month the bleeding is barely there, another month it is heavier than usual, sometimes it stops, you think it is over, and then a few days later brown or dark red bleeding starts again.

If this is happening to you, the first thing to understand is that perimenopause does not simply mean your hormones are gradually getting lower, because what often changes first is their rhythm.

Your ovaries are still active, but they are becoming less predictable, some months they may work almost exactly as they always have, but in another cycle, ovulation may happen much later, or it may not happen at all. Oestrogen may rise strongly, fall, and then rise again, while progesterone production may be perfectly adequate in one month and very low in the next one. And because your menstrual bleeding is the end result of everything that happened hormonally earlier in the cycle, the period itself often becomes one of the clearest signs that this internal rhythm is changing.

What typically happens in a normal cycle?

During the first half of the cycle, oestrogen rises and helps the lining of the uterus (the endometrium) grow, then ovulation happens. After ovulation, the follicle that released the egg becomes the corpus luteum (yellow body) and starts producing progesterone, which is important to helps stabilise and organise the uterine lining. If pregnancy does not occur, oestrogen and progesterone eventually fall and that hormonal withdrawal triggers a period.

When ovulation becomes unreliable, this beautifully organised sequence becomes less reliable and this is where many of the strange bleeding patterns of perimenopause begin. A period that suddenly comes late may simply mean that you ovulated later than usual. If you previously ovulated around the middle of the cycle but this month ovulation happened ten days later, your period will naturally come later too.

But sometimes a long cycle does not contain ovulation at all, in that case, the ovaries may still produce enough oestrogen to stimulate the uterine lining, but there is no normal rise in progesterone afterwards, so eventually that lining becomes unstable and begins to shed. This bleeding may look like a period, but hormonally it was not the end of the same type of cycle you may have been used to in your thirties.

That distinction is useful because it explains why some perimenopausal periods simply feel different.

* Perhaps the bleeding is very light

* Perhaps it is mostly brown

* Perhaps it lasts longer than usual without ever becoming particularly heavy

* Perhaps it starts and stops

All of these can happen when the endometrium has not been built and stabilised in the usual way. A very light period can sometimes mean that relatively little uterine lining developed during that particular cycle, oestrogen stimulation may have been lower, follicular development may have been weaker or delayed, or the entire hormonal sequence may simply have been less coordinated than usual.

But the opposite can happen too. Some women suddenly experience much heavier periods in perimenopause, sometimes with clots or several days of very heavy flow. This can happen when oestrogen continues stimulating the uterine lining but ovulation does not occur normally, and without the usual progesterone phase, the lining can continue to develop and become more unstable. Eventually it sheds, and there may simply be more tissue and blood to lose.

This is why it is misleading to think of perimenopause as a simple state of low oestrogen.

Oestrogen can actually fluctuate quite dramatically during this stage, some cycles may involve relatively low oestrogen activity, while others may contain strong oestrogen peaks.

Progesterone is often a different story, because progesterone depends heavily on ovulation, and no ovulation means no normal corpus luteum. Without a normal corpus luteum, there is no normal post-ovulation rise in progesterone, and this is one reason the relationship between oestrogen and progesterone can change so much during perimenopause.

You may have heard the term “oestrogen dominance”, so I prefer to explain it a little more carefully, because it does not necessarily mean that oestrogen is constantly very high. Sometimes it simply means that there is significant oestrogen activity without enough progesterone following it, because ovulation has not happened normally. So the issue is often not just how much of each hormone is present, but whether they are appearing in the right sequence, and this brings us to one of the most confusing bleeding patterns of all: the period that seems to finish and then starts again.

Let’s imagine, you bleed for several days, then nothing for 3 or 4 days, when brown or dark red bleeding begins again. It is very easy to assume that something must be wrong or that you have somehow started another period immediately, however this second bleeding does not necessarily represent a completely new cycle. If the uterine lining is shedding irregularly, it may not all come away at once, one part may shed during the first episode of bleeding, while another part remains and becomes unstable later. The result may be several days of bleeding, a short break and then another episode of light bleeding or spotting. The darker colour often simply means that the blood has taken longer to leave the uterus and vagina and has oxidised before appearing, so the colour itself is usually less informative than the overall pattern.

Another common experience is prolonged spotting, so instead of having one clear period, you may have a few days of brown discharge, then nothing, then a little pink or red bleeding, then several more days of spotting. This can be especially frustrating because it feels as though the period never really starts and never really finishes. Here again, irregular ovulation can be part of the explanation. If there is enough oestrogen to stimulate the endometrium but not a normal progesterone phase afterwards, the lining can become unstable in different areas at different times. Rather than receiving a clear sequence of signals to grow, stabilise and then shed, the endometrium begins breaking down unevenly and this can be the reason irregular spotting can become so common in perimenopause.

Then there are the cycles that seem to disappear altogether, which means you may miss one period, then another. 6 or 8 weeks pass, then suddenly you have a completely normal-looking period again. This can be confusing because many women assume that once periods start disappearing, the ovaries are steadily shutting down, however perimenopause is rarely that orderly. Your ovaries can have a quiet month or more, and then become active again. A long cycle may contain no ovulation at all, but another long cycle may still contain a very late ovulation. This is also why irregular periods do not mean pregnancy is impossible, so until menopause has actually been reached, ovulation can still occur unexpectedly.

Short cycles can happen too, which means a period may suddenly return after only 18 or 20 days. Sometimes this is breakthrough bleeding rather than a true new menstrual period, but sometimes the next follicle really has started developing unusually early. In practical terms, this simply means that the ovaries can occasionally start working on the next cycle before the previous one has completely followed the pattern you would normally expect, so during perimenopause, you can genuinely move between very different cycle patterns within only a few months.

What can make this stage much easier to understand is to stop looking only at the date your period starts, because your bleeding pattern contains much more information than that. Start noticing how long the cycle was, how many days you actually bled, whether the flow was spotting, light, moderate or heavy, whether it stopped and restarted, whether there were clots and whether the bleeding was associated with pain.

It can also be useful to notice what was happening in the rest of your body.

Did you have breast tenderness before the bleed?

Changes in cervical mucus?

Headaches?

Poor sleep?

Hot flushes?

A sudden change in mood?

Those details may help you recognise whether there are still signs of ovulation in some cycles and how your wider hormonal pattern is changing. One unusual period usually tells us very little, but several months of tracking can tell us much more.

It is also important not to assume that every unusual bleed is automatically caused by perimenopause. Hormonal changes are extremely common during this stage, but fibroids, polyps, adenomyosis, thyroid problems, some medications and changes in the endometrium can also affect bleeding. There is one important line that should always be remembered: once you have gone 12 consecutive months without a menstrual period, you are considered postmenopausal. Any vaginal bleeding after that point should be assessed, even if it is only a very small amount of spotting.