3 year old

My three year old son constantly wants me to play with him. To the point where he won't play alone and is asking me to play with him non stop when were home. I am 22 weeks pregnant with my second child and have been super exhausted lately. I play with him quite a bit, but have been encouraging him to play by himself lately so I can get a bit of rest or to get stuff done. He still doesn't take no for an answer and continues to ask me to play with him non stop. Anyway, I'm wondering if anyone else is going through this or has gone through this? I love playing with him but just can't do it all day, everyday.