Did you know that on the day your baby is conceived you are already two weeks pregnant??!!
It doesn't sound right but that's how gestational weeks are calculated.
The doctor can at some point change expectant mothers’ due date.
However, if the date of the last menstrual period was accurate, an allowance of a week before or after the due date is considered fairly accurate.
This is how your pregnancy health care provider will calculate your due date.
If you have irregular cycles you can ask about a 'dating scan' an ultrasound done around the six-week mark, which calculates the due date based on embryo size.
A regular menstrual cycle is one where the duration between menstrual cycles is 28 days.
But in case of irregular cycles, the following methods can be applied.
Most pregnancies last 40 weeks (38 weeks from the actual conception date).
Basically, the start date of your pregnancy is actually the first day of your last period - Day 1 of your menstrual cycle.