Returning to work after staying at home will be an adjustment. Here are some tips for managing the transition.
First, get onboard with the fact you're going back to work. You shouldn't feel guilty about wanting to continue your career, if that's your choice. If you're returning to work out of financial necessity, don't feel guilty about that either. You're doing what needs to be done to take care of your family.
Once you do return to work, acknowledge that everyone's schedule just became a lot more complicated; so you'll need to do a lot more planning to make sure everything gets done. A calendar can help, but the key is constant communication between you and your spouse, and anyone else involved in caring for the family (e.g. nanny, grandparent or babysitter). If you are lucky enough to have a support system to help share the load, don't be afraid to delegate.
Do understand that transitioning back to work will be a process both for you and your child; so give both of you time to adjust. Whatever childcare arrangements you've made for your child while you're at work, start using them before you actually return. This way, you can iron out any wrinkles before your time is occupied by your new schedule. When you do actually return to work, don't expect yourself to be at 100% productivity the day you get back. Try to return on a Wednesday or Thursday, so your first week back isn't a full week. Also, give yourself time to get to know new faces or new priorities around the office.
Lastly, keep work at work, and be with your family when you're with your family. It might be impossible to build an impenetrable wall between them, but keep that wall as high as you can. Make sure you're giving your relationships at work and at home the time they need, so neither suffers.