Some women, as they recover from hypothalamic amenorrhea (missing periods), will be worried that they are ovulating “late” in their cycle, maybe Cycle Day 21, 22… but then they get their period around the normal time, maybe CD 28-30.
In some cases, and this was true for me, the issue is the short luteal phase (the time between ovulation and when your period arrives) leading to a seemingly long follicular phase (time between period and ovulation).
When I tracked my ovulations and periods carefully I noticed that my ovulations were routinely 28-30 days apart, as expected. So it wasn’t that the ovulation was messed up, it was more that my period wasn’t aligning with the ovulation as in a normal cycle. A similar phenomenon was observed in a research study where women with short luteal phases were observed to have longer follicular phases (this was not the main focus of the study, but my observation from data reported in Table 2).
My theory is that to some degree, our period and then subsequent ovulation are actually hormonally separate events. The period comes because of a drop in progesterone, that is unrelated to the decrease in estrogen that primes the small increase in FSH to start the new follicle growing. So in a woman with a short luteal phase, the drop in progesterone occurs early, leading to an early period – but that does NOT drive the start of follicular growth, which waits for a few days and then begins, on its regular 28 day cycle.
I know this is confusing, so check out these diagrams. Here’s a normal cycle…the small increase in FSH at the beginning leads to growth of the egg-containing follicle. In the middle of the cycle, around CD12-13, LH spikes leading to ovulation around CD14. After ovulation, the follicular structure collapses into the “corpus luteum” which starts secreting progesterone by around CD16. When progesterone levels fall approximately 12 days later, the period starts, FSH increases, and the whole cycle begins again – with ovulation around CD14 and period around CD28.
Here’s my view of what is happening when one has a short luteal phase. Let’s imagine that the first period in this diagram was induced by Provera and then Clomid is used to start the follicular growth. So the follicular phase proceeds just as above – a small increase in FSH leads to growth of the egg-containing follicle, LH spikes around CD12-13, and ovulation happens on CD14. This is where things aren’t working quite right – the corpus luteum forms, but isn’t making enough progesterone. So the increase in progesterone is lower, and for a shorter amount of time. This leads to an early period – in this diagram, about a week early, for a 6 to 7 day luteal phase.
This leads to what I’m terming the “apparent cycle day” in the figure – menses have started, so ostensibly it’s CD1 again. However. The OTHER hormones involved in the cycle are not at CD1 levels yet. They are still at CD22, 23, 24 levels. The estrogen needs to drop further to instigate the increase in FSH to start the follicular growth… and THOSE hormones are not affected by the lack of proesterone. They continue along their merry way as if it’s CD 22-28, not caring that you’re bleeding already and *think* it’s CD1. So then you get to CD14 and think that ovulation should be happening… but it doesn’t. So you get frustrated (trust me, I know!!) But in reality, your other hormones are on their normal 28-30 day cycle, when when you get to where CD14 would have been if your period had come on time at CD28, that’s when you ovulate. Does that make sense? If not, feel free to drop a question in the comments!
To further illustrate this, here’s a table with my cycle data (this was after my second son was born in September 2008… my first postpartum ovulation was 7/29/2009 while I was still breastfeeding morning and night. I got my period just five days later on 8/3/09, for a four day luteal phase. This cycle isn’t a great example as the cycle is long as is common in initial postpartum or recovery cycles. However the next one (cycle #2) is a perfect example. After only a six-day luteal phase, I got my peiod on 9/15/09 – had it been a normal length LP (e.g., CD14 ovulation, CD28 period start), my period would have come on 9/21/09 instead. I then ovulated on 10/6/09, which based on when my period actually started was apparently CD22… but had my period come when it “should have”… the ovulation would have been CD15.
One anomalous cycle happens on cycle 10 – I had gotten pregnant the cycle before, but unfortunately had a miscarriage that was resolved after two D&Cs. After that I started to use progesterone suppositories to support my luteal phase, which leads to close to normal LPs and pretty close to CD14 ovulation. I did NOT use progesterone on cycles 15 or 16… leading to shorter luteal phase and apparent later ovulation!
You can see from this data set that there’s a fair bit of variability between cycles – compare the days between ovulation and you see that mostly they’re around ~28-30 days, but there are a few that are shorter, and a few that ar longer. I know that some women are like clockwork, but that is certainly not true for me!!
I hope this helps explain why a short luteal phase and longer apparently follicular phase are associated – again, feel free to ask any questions you may have – or please share if this has been your experience as well – or not!
P.S. Check out Chapter 19 in No Period. Now What? for a LOT more information on luteal phases, why they might be short, and what you can do about it!!