The opossum has the shortest gestation period of just 12 to 13 days. Human gestation takes about 280 days, for comparison. In humans, males often require a longer gestation period of a few days than females.
More Reproduction Facts:
- Elephants have the longest gestation periods: 616 to 645 days.
- In a human, a baby born in less than 37 weeks — 3 fewer weeks than the average 40 — is considered premature. Five of every 100 human babies is over due, or taking more than 42 weeks to come out.
- Doctors give women an estimated due date when they get pregnant. Only 4% of women actually give birth on that day.