38 weeks pregnant
Doctors count pregnancy from the first day of the last period. This page shows what week 38 looks like in dates and lets you work out your own due date.
How it works
Due date equals the first day of your last period plus 280 days. Weeks along equals days since that first day divided by 7, rounded down. Week 38 is 266 days.
Worked example
The first day is 3 February. Add 266 days to get 27 October. 266 divided by 7 is 38 weeks. Add the 14 days still to go and the total is 280. The due date is 10 November. The year in this example has 365 days.
Common questions
Which trimester is week 38?
Third trimester. The first trimester covers weeks 1 to 13, the second covers weeks 14 to 27 and the third runs from week 28 to the birth. Week 38 is week 11 of the third trimester.
Why do weeks start from the last period and not conception?
Most people know the date of their last period but not the day of conception. Counting from the last period gives everyone the same starting point. A pregnancy is about two weeks longer on paper than from conception. Counted from conception, this would be week 36, which is 252 days.
How accurate is a due date?
Only a small share of babies arrive on the due date. Most arrive within a couple of weeks either side. Treat the date as the middle of a window. Here the due date is 10 November, and 14 days remain from week 38.
What if my cycle is not 28 days?
The 280 day rule assumes ovulation near day 14. If your cycle is much longer or shorter, your doctor may adjust the due date, often with an ultrasound. With a 35-day cycle some clinicians add 7 days, which would move 10 November to 17 November.
Does a leap year change the due date?
It can. A year with an extra day in February moves dates after that day by one. The calculator above uses the real calendar for your dates. If the span from 3 February includes a 29 February, 10 November reads one day earlier, as 9 November.