I don't recall this from my previous pregnancy, but perhaps that was because I didn't have a 2yo then. I'm 33 weeks and all I've done this week is lose my shit with him.
I'm not a pleasant person to be around, and I feel horrendously guilty that the new baby is causing me to behave this way towards my first baby, whom I usually have a great relationship with.
He must be really confused and upset that mummy a) can't and won't get on the floor and play with him anymore, b) can't and won't carry him around (he's 17kg ffs!), and c) has zero patience for any normal toddler behaviour.
I feel like shit and I can see in his face that he doesn't understand. I don't want him to resent the baby (I'm only having a bloody second for his benefit when they're older).
I'm also panicking about how I'll behave towards him when the baby is here and I'm even more hormonal and tired.
I had severe PND and psychosis last time around and I'm acutely aware of not wanting to frighten DS if it happens again. But I'm already behaving inappropriately. Poor DS 
Moan moan moan.