For me it was hard being pregnant and dealing with my comprehensive exams, especially the oral exam, during which I started feeling dizzy and had to run into the bathroom and cry for 15 minutes. When I came back to the room the professors, who were all male, softened their tone considerably. It was amusing and humiliating at the same time. My dissertation proposal defense was a week before Sam was born and that was a lot easier for some reason. No crying. So who knows.