When asking "how many days pregnant are you", it typically refers to how the healthcare system counts pregnancy in weeks and days. In Denmark, the length of pregnancy is most often calculated from the first day of your last menstrual period (LMP), not from conception itself. Therefore, at the beginning, you may be "dated" as pregnant before the egg is actually fertilized. This can seem confusing, but it makes it easier to calculate for everyone.
How many days does a pregnancy last?
A pregnancy is often stated as 40 weeks, which corresponds to 280 days, when counted from the first day of the last menstrual period. This is a standard calculation used to find an expected due date.
Important to know about the number 280 days
The 280 days are a starting point, not a guarantee. Some give birth before the due date, others after. Your midwife or doctor can help assess what is most likely in your specific situation.
How pregnancy weeks and days are counted (0-6 days)
Pregnancy is often written as week+days, e.g., 12+3. This means:
- 12 weeks and 3 days along
- where "the days" are counted from 0 to 6 in each week
Example of the week format
- 12+0 is the first day of week 13 (you have completed 12 weeks)
- 12+6 is the last day of week 13
- the day after 12+6, you become 13+0
This is precisely why you may find that apps, due date calculators, and scan notes use this notation.
Calculation from last menstrual period (LMP)
If you know the date of the first day of your last menstrual period, you can fairly easily find out how many days you have been pregnant according to the standard method.
Practical step-by-step
- Find the date of the first day of your last menstrual period (LMP)
- Count the number of days from LMP to today
- Divide the number into weeks and days
- Weeks = number of days / 7 (whole number)
- Days = remainder (0-6)
For example, if you have counted 87 days since LMP:
- 87 / 7 = 12 weeks (12 x 7 = 84)
- Remainder 3 days
- You are 12+3
If your cycle is very irregular, the LMP calculation may be inaccurate. In this case, an early scan can often provide a more precise dating.
Due date and due date calculator - what does 40 weeks mean?
The due date is an expected date, often calculated as 40+0 (280 days) from LMP. Many use a due date calculator to get:
- estimated due date
- current pregnancy week and day
- overview of milestones (e.g., scans)
When scans change the due date
During an early scan, the due date can sometimes be adjusted if the size of the fetus suggests that you are earlier or later than calculated from LMP. This is quite common and does not mean that you have done anything wrong.
FAQ: Typical questions about "how many days pregnant are you"
Why is it not calculated from conception?
Because the exact time of conception is rarely known precisely, while the first day of the last menstrual period is often easier to date.
How many days pregnant are you when the test is positive?
This varies, but many test positive around the time of a missed period. In LMP calculation, this often corresponds to approximately 4+0 or later, but it depends on cycle length and test timing.
Can different apps show different weeks and days?
Yes. Small differences can be due to the method the app uses (LMP, ovulation, scan) and how it rounds days.
Products that can be helpful as your body changes
Once you have a better overview of how many days pregnant you are, it can also be a good time to consider if your body needs extra support in everyday life. Many pregnant women prefer soft solutions without underwires, as the body and breasts change continuously.
An example is a nursing and maternity bra with gel support as an alternative to metal, e.g., Gel-Support® Maternity & Nursing Bra. If you are looking for support for your stomach and lower back, a support belt may be relevant, e.g., Maternity Support Belt.
Sources for the principles of calculation and week/day format include praksisjordemoder.dk, baby.dk, and canacare.dk (due date calculator and explanations about weeks and days).