Congratulations!! Well your four year old will be starting school so she will be busy with that. There is always some adjustment when a new child is born though, but she should be fine. Maybe get one of those new baby brother or sister books to read to her and let her see that she can be the big sister and help her mommy with the new baby and that will make her feel special. If there are family members that could help take her to the park or something when the baby is born that will be good also. Mine are 10, 7, 5, 4, and 9 months.
I felt this way when I first found out I was pregnant with my second child but once she was born and I seen how close they were it went away 10 months apart