Maternity leave stress

Anyone else feeling stressed about maternity leave? I have been feeling really stressed about taking the three months off work. I'm really working toward a promotion and i have been at my job the longest of all the staff and have had great feedback and support for this change. We have a new staff that is hard core riding my coat tails and all I can think about it what she is going to do to try to step into my place when I'm gone. We are also hiring another staff that will be starting soon. Idk if I'm being unreasonable or not, it's just a constant worry. Anyone else feeling this way?