4 doctors weighed in:
How will my doctor calculate my due date?
4 doctors weighed in

2 doctors agree
In brief: By your LMP
The average length of a pregnancy is considered to be 38 weeks from the time of conception or 40 weeks from the first day of the last menstrual period (assuming you have a regular 28 day menstrual cycle).
That is an average so many women will have their babies before or after the calculated date. An ultrasound early in the pregnancy can help confirm an expected due date.

In brief: By your LMP
The average length of a pregnancy is considered to be 38 weeks from the time of conception or 40 weeks from the first day of the last menstrual period (assuming you have a regular 28 day menstrual cycle).
That is an average so many women will have their babies before or after the calculated date. An ultrasound early in the pregnancy can help confirm an expected due date.
Dr. Katherine Sutherland
Dr. Katherine Sutherland
Thank
In brief: Due date
Based on your last menstrual period: lmp - 3 months + 7 days.

In brief: Due date
Based on your last menstrual period: lmp - 3 months + 7 days.
Dr. Ecaterina Sartina
Dr. Ecaterina Sartina
Thank
Read more answers from doctors