I’ve been getting this too and for me the midwife said it might be related to the fact my blood pressure is quite low. I normally get it when I stand up from sitting down or move suddenly etc x
I have had this a couple of times and had low blood pressure when I got checked out at the doctors x
Yeah I get this when my BP drops too low xx
Most likely low iron, I’ve always had low iron so get this quite often, especially in the shower, mention this to your midwife next time as they should carry regular blood tests, one of the first things they check is iron anyway x