Human gestation is estimated as 40 weeks counting from the last menstruation. Conception is 2 weeks after that on average, so the actual time is about 38 * 7 =

Human gestation is estimated as 40 weeks counting from the last menstruation. Conception is 2 weeks after that on average, so the actual time is about 38 * 7 = 266 days. Dividing by 30, you get 266 / 30 = 8,866666666667 months (almost nine).