Most pregnancies last around 40 weeks (or 38 weeks from conception), so typically the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period (LMP). Another way to do it is to subtract three months from the first day of your last period and add seven days.

How are pregnancy weeks calculated?

Last menstrual period (LMP): Pregnancy normally lasts about 40 weeks from the first day of your last period. Accordingly, the number of weeks that have passed since indicate what week of pregnancy youre in. To work out your likely due date, count 280 days (40 weeks) from the first day of your last period.

How are pregnancies dates?

The most common way to calculate your pregnancy due date is by counting 40 weeks from the first day of your last menstrual period (LMP). And thats how most healthcare providers do it.

What is 1st week of pregnancy?

Week 1. This first week is actually your menstrual period. Because your expected birth date (EDD or EDB) is calculated from the first day of your last period, this week counts as part of your 40-week pregnancy, even though your baby hasnt been conceived yet.

Is pregnancy 10 months or 9 months?

A full-term pregnancy is roughly 40 weeks or 280 days (give or take up to 7 days) since your LMP. Of course, 40 weeks is generally thought of as 10 months, rather than 9 months. The variation in the number of days per calendar month, however, accounts for this discrepancy.