I'm asking because I've heard second hand of some women missing periods and some pregnant women having less than stellar reactions. I'm still trying to gather info and figure out how much of that is FUD and bs, and how much is actual issues that weren't caught by studies because of sample sizes or whatnot.
Look up Midaat organization in Israel that compiles information on vaccine safety and combats FUD. In short, there are credible reports, however it hasn't been determined yet if the effects are physical or psychological. For example, when there are wars in Israel, there is a similar surge of complaints.
Regardless, difference in the menstruation cycle can happen as a result of a positive immune effect, and likely don't represent any problem.