So my 2yr old son has been clinging on to me the last 2weeks and especially when i drop him off to the daycare(that hes been going to since he was 2months) and this morning when i dropped him off he was of course clinging to me and crying and the teachers was like "you're expecting" thats why hes acting that way.

I have heard of that happening after the baby was here, but has he recently been moved to a new teacher or something? If there was anyway I might drop by unannounced a couple of times during the day, sounds like he maybe got a new teacher and isn't adjusting that well, or it could be that he is 2,, my son sometimes acted that way, but not EVERY day,,

Yes it's like the child has a 6th sense. Little ones are more clingy when a new one is on the way. Are you expecting?

When I got pregnant with my youngest, my 2 year old began to get super clingy. She never wanted to leave my side. She also kept trying to nurse off me which she had been weaned for a while. At that time she was just over a year old.

babies can sense things, some are more sensitive to stuff like that than others. so it could very well be.

They can be very responsive & that's a common one. Which is why the daycare providers mention it.
I tend to think the situation builds because of a cycle within it, a cycle of resistance that triggers the child's counter-resistance or basically reinforces the child's clinging. (I know my response was to resist the clinging in some way, even when I was technically "accepting" or allowing it, because I had a negative response and "defending against" it by pushing/pressuring them NOT to be that way, or even just wishing it would stop, tends to reinforce it.)
There is a saying, "What you resist, persists." Also what you focus on, you get more of (and wanting something to stop, or not to be happening, or dreading it/worrying that it will happen at the next drop-off, are attention focused on the unwanted thing.)
I think this is the real reason these cycles happen, & yes it's about acute sensitivity to subtle things.

So, you don't know if you are pregnant at the moment? I don't think a child can cue in that early. A child knows when you're showing and planning.

On the other hand, two year old's are in are in prime separation anxiety territory by their age alone. Even children that have been used to to day care or other similar environments from a young age can experience it. It's very normal. Is this a new teacher? Have there been other changes in his world? Is he feeling 100%? Has he recently mastered a new skill or ventured into new more independent territory? These are all things that can spark a little cling. The good news is that it's typical temporary. Just reassure him. Like girlwithC says, how you respond can influence how clingy he remains for how long. A nice hug and a "Oh, I'll miss you too buddy!" goes a lot farther in helping him overcome this stage than something that pushes back on his feelings.