If you are a working mom you might probably feel bad about taking the maternity leave. Moms who are pregnant are generally not offered promotions or are usually not assigned important projects. This is because it is felt that pregnant women cannot do justice to their jobs.
This might be a temporary speedbreaker to your career. And it can make you feel depressed (another side effect of pregnancy hormones). If you are indeed feeling insecure about your job, have a frank discussion with your supervisors to ensure that the transition is smooth for both you and the workplace.