Final answer:
A prolonged pregnancy goes beyond 40 completed weeks of gestation, which is past the typical full-term duration of 38 to 40 weeks.
Step-by-step explanation:
A prolonged pregnancy is a pregnancy that has advanced beyond 40 completed weeks of gestation. Full-term pregnancy typically lasts around 38 to 40 weeks, measured from the first day of the last menstrual period (LMP). A fetus reaches a stage by the end of the 37th week where it has developed enough to survive outside the uterus with minimal risks associated with premature birth. Beyond 40 weeks, the pregnancy is often closely monitored by healthcare providers to ensure the health and safety of both the mother and fetus.