If you breakthrough bleed non-stop during continuous use on the pill is it because...?

[Walroz]

If you breakthrough bleed non-stop during continuous use on the pill is it because your uterine lining is building at the same time as being shed?
As far as I understand, oestrogen is responsible for building uterine lining. So if you are using the pill continuously (no break weeks) and you start to breakthrough bleed and it doesn't stop, is it because the hormones that you are 'feeding' your body are building the uterine lining at the same time as it is being shed? Is it even possible to build uterine lining while you're shedding it? I cannot find any literature on this!

Thank you!

[Heather]

Studies have found that people who do continuous, or extended use, experience about three times as much breakthrough (or, the newer term for it, "unscheduled") bleeding as those who use oral contraceptives traditionally, with 21 active days and 7 placebo or off-days, each cycle. Spotting wile using the pill like this is often just part and parcel of using it that way, as your healthcare provider directing this use can attest to (and hopefully told you about when they suggested this kind of use).

I'm not sure what you mean by "feeding" your body, or that I understand how you're conceptualizing all of this, but yes, uterine lining can be shed while it's also growing.

[Walroz]

Thank you!
I mean that, if you're breakthrough bleeding while you are taking active pills then you are still taking oestrogen and progestogen while you are bleeding. So I was wondering if it was possible that those hormones you are taking are building the uterine lining as it is being shed - essentially on a loop, so you get a 'never-ending period'. But you answered my question, so thank!