The election of Abraham Lincoln in 1860 was the immediate cause of southern resolutions of secession. He was the nominee of the Republican party with an anti-slavery expansion platform, he refused to acknowledge the right to secession, and he would not yield federal property within Southern states.
The gestation period of a human, from time of conception to birth is approximately 9 months (266 days/38 Weeks). 9.5 months is calculated from the first day of the last menstrual period (280 days/40 Weeks).
The interval of gestation period in humans is estimated to be around 40 weeks or 280 days. Gestation period in humans may normally last from 37 to 42 weeks or between 259 and 294 days. That means that in average pregnancy the birth occurs during this period of time.