"Circe" ) writes:
What have you heard? IUDs got a really bad reputation back in the 1970s due
to a bad product called the Dalkon shield. There is a small risk of
infection immediately following insertion, but that seems to be quite rare.
Other than that, I think that IUDs generally cause fewer health problems for
women than BC pills.

My understanding is that all IUD's involve something that can be
called infection. The uterus is normally free of bacteria, but
there is a zone around an IUD which contains bacteria. The zone
can vary in size and shape and type of tissue penetrated.
The question may be better phrased, not "is there an infection or
not," but "how extensive is the bacterial zone?"