280 days
More about your due date. It sounds a little silly, but you aren't really pregnant for about the first two weeks of your pregnancy. Pregnancy is calculated based on the average menstrual cycle (28 days), which begins with your period. About two weeks into this cycle, ovulation occurs... Once your pregnancy has been confirmed, what you most want to know is your due date. The average length of a pregnancy is 40 weeks, or 280 days, from the first day of the last normal menstrual period. Calculating the due date, or expected date of delivery, for a pregnancy is quite simple, then, if you know that date. Based on date of last normal menstrual period. Due dates are typically calculated based upon the date the last menstrual period began, according to the mother s report. Naegele s rule assumes that ovulation occurred 14 days after LMP, which is only the case for women with 28 day cycles. Due Date Calculator. This interactive Due Date Calculator will help you estimate the date your baby will arrive. Pregnancy usually lasts 280 days (40 weeks) from the first day of the woman's last menstrual period. This calculator is a general guide: every pregnancy is unique, and sometimes babies arrive sooner or later than expected. Always talk to your health care provider about your due date.
http://www.thebump.com/calculators/duedate http://health.howstuffworks.com/pregnancy-and-parenting/pregnancy/issues/10005-how-to-calculate-your-pregnancy-due-date.htm http://www.transitiontoparenthood.com/ttp/birthed/duedatespaper.htm http://www.marchofdimes.org/pregnancy/calculating-your-due-date.aspx
How is the due date for a pregnancy typically calculated? coursehero