Clearblue tests are accurate, easy to use and some digital versions tell you how long you've been pregnant. But they give you a different date to the NHS. So how far along are you?

One of the nail-biting parts when you're trying to conceive (TTC) a baby is waiting for to finally take a pregnancy test and getting an accurate result. Clearblue make one of the more popular pregnancy tests. Women like them for their accuracy ( 99% at detecting if you're pregnant, and 93% at telling how long you've been pregnant ). Research also shows they're among the easiest to use and read. Some digital versions even give you an estimation of how long you've been pregnant for.

However, the date that the tests give you can raise questions for some parents-to-be, as they don't line up with what you'll be told if you ask your GP or midwife how far along you are.

Wondering how to determine your due date based on your Clearblue pregnancy test results as well the guidance from the NHS? We're here to help!

• Check out our definitive guide on Days Past Ovulation (DPO), and how ovulation and conception works

Why Clearblue tests and the NHS provide different dates

If both methods are measuring pregnancy, it's natural to wonder how they can provide different results. They are both accurate. They simply use a different starting points.

According to the NHS , how long you have been pregnant is taken from the first day of your last period .

That's in contrast to Clearblue tests, which date your pregnancy from the date of conception . (That's because of how pregnancy tests work. See more about that below.)

So, because conception generally takes place around 14 days past ovulation , the dates are different.

Breaking down the timings

You start your period. This is when the NHS would measure from.

Around 14 days later, on average, you'll probably ovulate, if you have an average 28-day cycle. (You can try our handy ovulation calculator to work out when it could happen for you .)

Conception typically happens 12 to 24 hours after ovulation. This is when Clearblue will measure from.

So your Clearblue test date is taken from around 2 weeks after the date the NHS uses (depending on the length of your menstrual cycle, of course).

So how far along am I if my Clearblue test says 2-3 weeks?

As for determining how far along you are in your pregnancy, it's just a matter of doing a little easy math.

If your Clearblue test says 2-3 weeks, then the NHS would say that you're 4-5 weeks along .

Compare your test to the list below. However, you will need to adjust this slightly if you have particularly long or short cycles.

How do pregnancy tests work?

Once you become pregnant, your body starts to produce the pregnancy hormone human chorionic gonadotropin (hCG), which is what pregnancy tests are looking for.

• Head here for more information on when to take a pregnancy test

It normally takes until around 14 days past ovulation (DPO) before it builds up enough to be detected by most pregnancy tests.

That means that generally pregnancy tests will start to pick up if you're pregnant around the first day of your missed period. That's generally 28 days after the start of your last period, depending on your cycle.

Getting more information about pregnancy tests, TTC or to talk with other parents and parent-hopefuls, check out our Forum and further resources!

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