The Truth About Due Dates

As a journalist who's accustomed to meeting deadlines, I wasn't surprised when, during my first pregnancy, I went into labor on my due date. The second time around was another matter. My due date came and went. And went, and went, and went. It wasn't until the day before my doctor planned to induce me -- at nearly 42 weeks pregnant -- that I finally went into labor.

My experience brought home one of the essential truths of pregnancy: Your due date is anything but predictable. Still, your doctor needs to determine one that's as accurate as possible so that any necessary tests are done at the correct time. "And knowing how far along you are makes it easier for your obstetrician to see that your baby is growing properly," explains ob-gyn Joanne Stone, M.D., coauthor of Pregnancy for Dummies.