4 doctors weighed in:

Don't you count back 3 months from your last menstrual period, for the month you're due in? So, if my last period was april, i'm due in january? Right

4 doctors weighed in
Dr. Linda Gromko
Family Medicine
2 doctors agree

In brief: Always a puzzle!

Pregnancy is counted as 40 weeks in length - from the first day of bleeding of your last period.
This is based on that perfect 28 day cycle that everyone has! you aren't pregnant for 40 weeks - "only" 38! an ultrasound early in the pregnancy can predict your due date plus/minus one week. Check with your doctor about this, because it is important to be clear about your dates. Good luck.

In brief: Always a puzzle!

Pregnancy is counted as 40 weeks in length - from the first day of bleeding of your last period.
This is based on that perfect 28 day cycle that everyone has! you aren't pregnant for 40 weeks - "only" 38! an ultrasound early in the pregnancy can predict your due date plus/minus one week. Check with your doctor about this, because it is important to be clear about your dates. Good luck.
Dr. Linda Gromko
Dr. Linda Gromko
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David Miller
Family Medicine

In brief: Naegle's Rule

The standard way of calculating due date from last menstrual period is naegle's rule.
Add one year, subtract 3 months and then add one week to the first day of your lmp. Depending on when in april your period was, you should be due somewhere january or early february. In the clinic, we just use a "pregnancy wheel, " which does all this for us.

In brief: Naegle's Rule

The standard way of calculating due date from last menstrual period is naegle's rule.
Add one year, subtract 3 months and then add one week to the first day of your lmp. Depending on when in april your period was, you should be due somewhere january or early february. In the clinic, we just use a "pregnancy wheel, " which does all this for us.
David Miller
David Miller
Answer assisted by David Miller, Medical Student
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