The best way to help your friend who is pregnant is to simply be there for her. Ask her what she needs or how you can help.
Offer to handle a chore that is more difficult for her to do late in her pregnancy, such as scrubbing the kitchen floor or carrying bags of groceries inside and putting them away. Getting her a gift that will make her more comfortable or a special treat to satisfy a craving is also a great way to support a friend throughout her pregnancy.