Heavy breathing when lying down

Carolyn • 1st time 🤰 & waited so long for our little blessing. Can't believe this roller coaster of emotions of 1st time moms. 😁
Hi Nov17 mums, just wondering if any of you have experienced heavy breathing at night or only when lying down?
I find it odd because I haven't been doing any intense physical activities nor am I that big yet. I'm still on my 1st trimester (12th week). The heavy breathing lasts for about 5 to 10 mins. Sometime I also get it in the afternoon while standing up but it is more frequent while on bed.
Is this normal? First time pregnant here, would gladly appreciate your advice. Thanks in advance!