The New Health Guide reports that, as of June 2014, the longest pregnancy that was medically verified lasted for 375 days. The length of a normal pregnancy is about 280 days, or just over nine months.
In 1945, a woman named Beulah Hunter, who was 25 at the time, gave birth to a healthy, normal daughter named Penny Diana after the record-breaking pregnancy. According to the New Health Guide, the length of the pregnancy was verified by her menstrual cycle and the date of her positive pregnancy test. Doctors believe the lengthy pregnancy was due to the fact that the baby developed exceptionally slowly in the womb.