One of the ways that people use to determine your due date is a result of Dr. Naegele, in 1850. His way to tell your due date is based on a cycle of 28 days. If you use this way, you will do the following: To the first day of your last Menstrual Period (LMP) add seven (7) days to that date. Now subtract three months (3 months) and this will give you a due date.
EXAMPLE : If my last period started on November 2, I would add the 7 days, giving me a date of November 9th. Then I subtract 3 months, giving me a date of August 9th. This would be my due date, August 9th. Remember that this way does not take into account other factors such as: longer or shorter cycles, first time mothers, the fact that we have better health care today, and better nutrition, and that some women, African American and Asian women tend to have shorter gestation.
We will also use other ways to be sure of your due date.
fundal height. You measure one (1) centimeter above the pubic bone, for each week you are pregnant, this can also vary from two (2) centimeters above this to below this measurement and still be normal. EXAMPLE: if you are 32 weeks, you can measure from 30 to 34 centimeters and still be with in the normal range.
Quickening: The first time you feel the baby move. You should write this date down.
Fetal heart tones heard with a doppler or stethoscope.
CALENDAR MONTHS VS LUNAR MONTHS (10 months of pregnancy)
You carry a baby about 40 weeks or 9 calendar months. But you will notice that if you go by every 4 weeks, it comes out to be 10 lunar months. (moon phases) This is important to understand. If you are reading from some books that talk about 10 months of pregnancy, you will understand that they are not referring to ‘going over due’. They are talking about moon phases.