I think a big way to support someone who is pregnant is to just be joyfully willing to help. Sometimes it takes a lot to ask, but to not get annoyed when they ask you to get something for them to eat or their water bottle, but being positive and supportive in that manner in a huge difference.
The best way to support someone who is pregnant is to go over and help clean, nesting before or after the baby is there, and also just still trying to be their friend and still trying to hang out with them even whenever they have their new baby, but also when they're pregnant because they're going to have changes in energy and morning sickness and things like that, so just keep reaching out your hand.