My dog became aggressive since pregnancy

My dog used to be the sweetest thing. She rarely barks to other people nor to any dogs. I used to take her to the park and let her off leash and play with other dogs. But ever since I got pregnant I noticed changes on her behavior. She became very aggressive! She would bark on any people nearby when she's inside the house and bark at other dogs. She still sweet to visitors and strangers but just became aggressive when she sees other dogs. She hasn't got any fight so far but I couldn't take her to the park anymore cause of her aggressive behavior. There's no changes on her diet or sleeping pattern. She's updated with all her shots and doesn't show any symptoms of being sick. I'm guessing my pregnancy is affecting her. But is this normal? Any thoughts? I hope she'll go back to how she used to be after I deliver the baby. We're thinking of adopting another dog so she'll have someone to socialize and play with too.