Gestational Age: Understanding Due Dates and Post-Term Pregnancy

Question
How far overdue can you be ... without it being seriously dangerous for the baby?

Answer
When we assign a due date, we know that the patient can go into labor two weeks before or two weeks after the due date. We do not consider a pregnancy to be "post-dates" until 42 weeks gestation (14 days after the due date). We allow a patient to wait for two weeks after the due date before we induce the labor or deliver the baby. After 41 weeks gestation, we have the patient take a non stress test (NST) and a biophysical profile to assess fetal well-being, but if all is fine, we can safely wait until the patient reaches 42 weeks before deliving the baby.