Pregnancy Test FAQ’s – How Do Pregnancy Tests Work?

For all your home pregnancy test (HPT) questions and answers!

How Does a Pregnancy Test Work?

From the very beginning of your pregnancy, the foetus produces a hormone called hCG, or, human Chorionic Gondotrophin. This hormone is present in your urine if you are pregnant and increases as your pregnancy progresses, peaking at around 8-11 weeks, before dropping to a lower level at 12 and 16 weeks. Some pregnancy test kits can detect hCG levels as low as 10 or 25mIU/ml. If pregnant, at 10DPO (days past ovulation) you may be able to detect around 25mIU, at 12DPO 50mIU and 14DPO 100mIU.

Are Pregnancy Tests Accurate?

Home pregnancy tests have been shown to be over 99% accurate in lab tests. It is more likely you will get a false negative than a false positive if there was an error with the test.

How Soon Should I Test to See If I Am Pregnant?

As mentioned above, pregnancy test kits are designed to detect levels of hCG produced by your body if you are pregnant. Your body may be producing hCG before your period is due, however it is ideal to test on the first day of your missed period. If you were to test earlier than the first day of your missed period, the result may be incorrect. It may show a negative result if your hCG levels are not yet high enough to detect the pregnancy, or it may show a positive result and not develop into a true pregnancy due to the incidence of spontaneous abortions, which can occur before your period is due.

Is It True That It’s Best to Test In The Morning?

The pregnancy hormone hCG is usually at it’s highest levels early in the morning, so especially if you are early in your pregnancy, this is when it is the best time to test. It is important to note that excessive fluid intake before taking the pregnancy test can actually dilute hCG and this can make the result hard to read.

How Do I Best Use a Pregnancy Test?

It’s always best to follow the manufacturer’s instructions included with the test, as the procedure can vary and affect your result if not done properly.

As soon as you have taken the test out of the packet, avoid touching the absorbent pad. There are normally two ways you can perform the test, midstream or in a cup. If you prefer to test midstream, all you need to do is hold the test almost vertically and pass it through a weak stream of urine, making sure you avoid water or urine being splashed on the device before starting the test.

If you prefer to use the cup method, urinate into a clean, dry container and dip the absorbent pad into the urine for 3-5 seconds. You do not completely immerse the absorbent pad, 1cm is sufficient.

I Am Taking Medication; Will This Have Any Effect On The Test Results?

If you are taking antibiotics, the contraceptive pill, or painkillers, this should not affect the result of the test. If you are on any fertility medication which contain hCG, you may receive a false positive. Speak to your pharmacist or carer for more info. Clomid does not produce false positives for pregnancy tests, but it can on ovulation tests.

If The Test Result Is Faint or Hard to Read, Does That Mean I Am Not Pregnant?

It’s normal for the result on the pregnancy test to be either fainter or darker than the control line. The reason it may be fainter could be due to less hCG in your urine, especially very early in your pregnancy. It may be darker if your pregnancy is more progressed. Occasionally the test may display a ‘shadow’ line when the positive result should be, disregard this if you cannot see it when holding the test at arms length away from you.

How Long Should The Test Take to Work?

The test result should be read from 5 minutes and no later than 10 minutes. If any lines do appear after 10 minutes, it is still a negative result and must be disregarded. If you read the test sooner than 5 minutes, it may also be inaccurate as it has not had enough time to work.

What If There Are No Lines Visible At All On The Test?

It is unlikely that this will happen, but if it does, disregard the test. It may be due to not enough urine on the absorbent pad, too much urine on the absorbent pad or the test was not held correctly in the stream of urine. Repeat the test, carefully following the instructions as in the above question on how to use the test.

Should I Repeat The Pregnancy Test and If So, When?

If the result of your test was negative and your period still hasn’t started after a few days, test again. You may have miscalculated your cycle dates and / or the hCG level may be too low to detect. If you still receive a negative result after the second test and still have no period, consult your doctor. Some women find that they do not get a positive result as soon as others and some have only been able to detect pregnancy with a blood test. Everyone is different; however if you are concerned, do see your doctor.

What Should I Do If I Am Pregnant?

You should start considering options for pre-natal care, be it a midwife, Obstetrician, GP or combined care if you haven’t already. If you wish to see an Obstetrician you will need a referral from your GP. Many midwives, birth centres and Obstetricians do book out very quickly these days so be sure to make researching your options a priority. BellyBelly has some articles to help, Who Cares? Choosing a Model of Maternity Care, and Public, Private, Birth Centre or Home?.

What Can I Do If I Am Trying To Get Gregnant But Haven’t Been Able To?

It is normal for a couple to conceive anytime in the first twelve months of trying. You can try charting your cycle and/or using OPK’s (ovulation prediction kits), which work in the same way as pregnancy test kits – by measuring hormone in your urine. They can help you to identify your most fertile period by detecting LH which signals likely ovulation in the next 24-36 hours.

The BellyBelly Forums also offer great support for those trying to conceive over short and long periods of time, including assisted conception.

Where Can I Get More Help and Support?

BellyBelly has a section in the Forums dedicated to HPT’s and OPK’s – you can read others questions or post your own HERE. Alternately you can call the advice line numbers found on most pregnancy test kit packets or their information leaflets.

Kelly Zantey is the creator of BellyBelly and is a mum to two beautiful children. She’s also a Birth Attendant; you can read about BellyBelly Birth Support here.

To read more pregnancy articles, please click here.