Weird sleeping/breathing?

Another (odd) question... Maybe someone might have some sort of knowledge
about this, seeing as it definitely seems everyone seems to know their stuff
lol

When I sleep, I guess I kind of hold my breath. I actually didn't notice it
first. Laying in bed one night, N jabbed at me with his elbow (not hard,
just a little, 'hey, let me have your attention!' type thing) and told me to
simply "stop that". Confused, I asked what he was talking about and why
he's poking at me when I'm trying to sleep. He told me to stop holding my
breath. I didn't even know I was. He said that I have been doing it more
and more - and once he pointed it out, I did actually notice it, but I also
find that even now, when I notice it, it takes actual effort to think to
stop holding my breath. I also know that I don't hold my breath until I
pass out or anything like that. I don't feel light headed, more or less
tired/awake. It's a regular inhale, and then at the end of inhaling, my
breath is held, maybe 5-6 seconds. Then an exhale, and same thing, at the
end of exhale, hold breath for 5-6 seconds or so. Not each and every time I
breathe, but often enough. Often enough that N notices it at night and I
also notice it (he notices more than I do if we're both awake)

I'm not 100% sure when this started, but I know it hasn't happened all
along. It's been maybe the last couple months max. I think it was brought
to my attention about 2 or so months ago - shortly after I found out I was
pg. It seems to be something I'm slightly aware of every other night,
sometimes nightly.

Not sure if it's related or not to this pregnancy (never noticed this
before, pregnant or not) or if it's a concern. I still fall asleep and I
can't say for sure if it continues while I'm sleeping, but N says that he
notices it when I am asleep, although it's very seldom (happens more when
I'm going to sleep) and a simple jab is enough to make me shift or roll over
and stop doing it, even though I don't feel I'm actually doing it (or doing
it on purpose or being very aware of it)

Any ideas or has anyone ever heard of something like this before?