IIRC you're not in the US, but around here, it's cliche that nobody warns you about anything that messes with your cycle. I'd been on the Pill for years before I learned antibiotics can alter its effectiveness, and I didn't learn that from the doctor who prescribed it to me (who also often was prescribing the antibiotics). When I asked about it, he acknowledged it, but seemed a little annoyed with me. (He didn't like being questioned, which caused me to fire him halfway through my pregnancy with The Kid.)
More on topic: TIL vaccines can affect menstrual cycles. Not a concern for me anymore, but worth letting The Kid know. So thank you for that.
It's not just in the US, by the sound of it, although you might have it worse. But it's rather like since you have a womb, you're supposed to - idunno- intuitively know this stuff? Learn it from your mother or something? When no one told her either? The female hivemind?
For instance, I did not know that about antibiotics either.
It delays it, on average, from starting by less than a day. No effect on fertility. Heard an interview with a woman on author list of the study. If that's borking, my own system borked me that badly about 1/3 of the time anyway.
Yeah, no. A day of delay is not the only effect noted. People reported not just variations in starting date but also variations in length, volume and discomfort. Not all that many together I hear, over here they've only had a 1000 people report changes in their period.
(Still lots more than those with blood clots, just saying.) But I'm guessing there are probably more that didn't bother with reporting it.
I know I didn't, because I didn't think it was the vaccine. With a period that often borks all on its own, and no indication about a borked period being a possible side-effect, who thinks about a connection with the vaccine you had almost two weeks earlier? The side-effects I was warned about were all long gone by then.
I know I wouldn't even have
noticed a day delay. But my period right after the booster was the worst I could remember. I debated contacting my gynaecologist because it was that bad I was starting to think something was wrong. I couldn't
sleep the first night of my period as I was in too much discomfort.
Frankly, vertility was the farthest thing on my mind. I was seriously contemplating whether I could I
ask beg to have the whole lot torn out. "Free womb, one previous owner, never used, willfull bugger, will go to good home,
any home, frankly. "
TL;DR: Knowing ahead of time would have spared me quite a bit of discomfort and anxiety.