4 weeks pregnant
This calculator finds an estimated due date and how far along you are. The worked example is a pregnancy at exactly 4 weeks.
How it works
Start on the first day of your last period. Move ahead 280 days for the due date. Divide the days that have passed by 7 to get weeks. The remainder is extra days. Week 4 is 28 days.
Worked example
Use 13 April as the first day. Add 280 days for a due date of 18 January. Week 4 starts 28 days in, on 11 May. 28 divided by 7 is 4. Subtract 28 from 280 to get 252 days to go. This example assumes a 365-day year.
Common questions
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 18 January to 25 January.
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. The span from 13 April does not cross February. A leap year changes nothing for 18 January.
How many months is 4 weeks pregnant?
About 0.9 months. A pregnancy is 40 weeks, a little over 9 calendar months. Months are only a rough guide. At 4 weeks there are 252 days to the due date.
Which trimester is week 4?
First 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 4 is week 4 of the first 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 2, which is 14 days.