You're pregnant and by choice or by chance you're doing it without a partner, Dr. Leah, author of The Complete Single Mother says you may be overwhelmed and with good reason, ''Single motherhood is relentless. You are the person in charge, you are the person with all of the responsibilities, you're pretty much on 24/7.'' So how can you make this work? Dr. Leah says the first thing that you need to do is process any sadness that you may feel about not having a partner to share this experience with you.