For a variety of reasons, re-entry from a maternity leave to the same job can be very challenging. Personally, you are likely to be very tired from nights on end of interrupted sleep. Many women are sad to be separated from their babies. Especially if this is your first child, you are now adjusting to life as a working parent. Even if you are already a parent, a new family routine must be established with each new child. A routine takes both time and energy, both of which are limited resources with a new baby in the house. Just the practicalities of having a new person in the house in terms of getting out the door in the morning can be daunting.
Professionally, there will be considerable work waiting for you upon your return. If you have a continuity clinical practice, your patients may have waited to see you which creates an increased demand for your clinical attention right when you get back. Alternatively, they may have seen a covering doctor in your absence, in which case you will need extra time to get caught up on what happened with their care while you were away. Even if you looked at your email while you were on leave, there are likely to be many administrative or academic tasks that now need to be actively addressed.