Taking a pregnancy test can be an anxious and emotional experience for many women. With home pregnancy tests being relatively inexpensive and accessible, the temptation is high to take one as soon as you suspect you might be pregnant. This often leads women to take pregnancy tests at all times of the day or night. But is testing at night reliable? Or is it better to wait until the morning?
The short answer
Yes, you can take a pregnancy test at night and expect accurate results. There is no medical reason why the time of day would affect the accuracy of a pregnancy test. Most modern home pregnancy tests measure the pregnancy hormone hCG, which is present in urine at all times of the day in roughly the same concentrations.
How pregnancy tests work
To understand why time of day doesn’t matter, it helps to understand how home pregnancy tests actually work.
When a woman is pregnant, her body produces the hormone human chorionic gonadotropin, or hCG. This hormone is what signals to the body that pregnancy has occurred and prevents menstruation.
Home pregnancy tests detect the presence of hCG in your urine. The level of hCG increases steadily during early pregnancy. Most tests are sensitive enough to detect hCG levels around 25 mIU/mL.
Modern home pregnancy tests work by immunoassay – they contain antibodies that bind to the hCG in your urine. This triggers a color change on the test, producing the familiar positive or negative lines.
hCG levels remain stable
The key point is that hCG is present in your urine at all times of day at roughly the same concentration. So unlike many other substances in your urine that can fluctuate, the pregnancy hormone remains steady.
In very early pregnancy, hCG levels double every 48-72 hours. So there isn’t significant hourly fluctuation – at 3 weeks pregnant, your hCG levels on Tuesday morning will be similar to Tuesday night.
There is a slight variation in hCG concentration depending on how diluted your urine is. But this minor fluctuation isn’t significant enough to affect test accuracy or whether a positive result is achieved.
What impacts pregnancy test accuracy?
If hCG levels themselves don’t change much throughout the day, what factors can impact the accuracy of a pregnancy test?
Timing of implantation – A fertilized egg takes 6-12 days to implant in the uterus before hCG is produced. Testing too early means there is no hCG to detect yet.
Sensitivity of test – Home pregnancy tests have varying sensitivities, with some detecting hCG at levels as low as 10 mIU/mL. Choose an early detection test for the most accuracy.
Following test instructions – Failing to follow the directions properly can lead to incorrect results.
Medications containing hCG – Certain fertility medications that contain hCG can produce false positives on home tests.
Dilution of urine – Very diluted urine could prevent an accurate reading.
But the time of day or night is not a major factor in the reliability of results.
Are there any cons to taking a pregnancy test at night?
While time of day doesn’t affect if a pregnancy test is accurate or not, there are some potential disadvantages to taking one at night:
– You may get an inaccurate result if your urine is very diluted after drinking a lot of fluids in the evening. Using first morning urine can help avoid this issue.
– If the test gives an ambiguous or invalid result, you may have to take another one in the morning anyway.
– You won’t be able to follow up on the result with your doctor until the next working day.
– A negative result could lead to lost sleep due to worry or stress. Or a positive could make it hard to sleep due to excitement.
– Your partner or support person may not be present to share in the moment.
– Lighting may not be ideal to clearly see the test result.
For some women, waiting until morning is preferable so they can take the test with ideal conditions and support. But many also wish to take a pregnancy test at night for the privacy and ability to process the result overnight.
Tips for accurate results at night
If you do decide to take a home pregnancy test in the evening or overnight, here are some tips:
– Try not to urinate for at least 2 hours beforehand to avoid diluted urine.
– Read the test within the timeframe specified in the instructions, usually 3-5 minutes. Don’t read it after longer than 10 minutes.
– Check the test under good lighting, like in a brightly lit bathroom.
– Retest with first morning urine if the result is ambiguous or negative but your period is late.
– Choose a test with high sensitivity for early detection. Look for tests detecting levels of 25 mIU/mL or lower.
– Confirm any positive result with a blood test at your doctor’s office. Home tests can occasionally deliver false positives.
Interpreting faint lines
You’re more likely to encounter faint lines on a pregnancy test taken at night or with diluted urine. Even faint lines indicate a positive result, as long as they appeared within the test timeframe. But a faint positive could mean:
– You’re testing very early, and your hCG levels are still low but rising. Retest in a few days.
– Your urine was dilute. Recheck with concentrated morning urine.
– Evaporation lines that appear outside the timeframe may indicate an invalid result.
– In rare cases, a faint line can indicate an ectopic pregnancy, miscarriage or other abnormality. Get checked by your doctor.
Sleep tips after taking a pregnancy test at night
Whether the result is positive or negative, taking a pregnancy test shortly before bed can understandably make it difficult to sleep. Here are some tips to help get rest after nighttime testing:
– Try relaxation techniques like meditation, deep breathing or listening to calming music. Even 10 minutes can lower anxiety.
– Avoid being on your phone or computer beforehand – the blue light and stimulation can make falling asleep harder.
– Have a small snack like yogurt or crackers if hunger is keeping you up.
– Write down your thoughts and worries in a journal to help clear your mind.
– Remember that worrying at night rarely changes the outcome – try to be kind to yourself.
– Share your result with a partner or friend if you need support processing emotions.
– Wake up your partner to immediately share if the result is positive and you’re too excited to sleep!
When to take another pregnancy test
If you take a home pregnancy test at night and get a negative result despite a missed period, when should you retest?
– Take another pregnancy test with first morning urine, which is least diluted.
– Wait at least 2-3 days before retesting to allow more time for hCG levels to rise.
– Consider using a test with greater sensitivity down to 10-15 mIU/mL.
– If it’s been more than 10 days after a missed period and tests remain negative, see your doctor to investigate further.
FAQs about taking pregnancy tests at night
Can I take a pregnancy test at night and first thing in the morning?
Yes, you can take a test at night and then again with first morning urine. The second test helps confirm the accuracy of the first.
Is it better to take a pregnancy test at night or in the morning?
Most experts recommend using first morning urine, as it’s the least diluted. But testing at night is reliable too as long as your urine isn’t overly diluted.
Why are pregnancy tests done with morning urine?
Morning urine is the most concentrated, making pregnancy hormones easier to detect. But testing any time of day typically gives accurate results.
Can you get a false negative pregnancy test at night?
You could get a false negative at night if your urine is very diluted. But if you haven’t had much to drink before bed, results should be accurate.
How late at night can you take a pregnancy test?
You can take a pregnancy test immediately before bed, even after midnight. Just be aware very diluted urine could affect the result.
Conclusion
While taking a pregnancy test with morning urine may be ideal, testing at night provides reliable results in most cases. HCG levels remain fairly steady throughout the day.
To get an accurate readout at night, concentrate your urine by limiting fluids beforehand and read the result in good lighting within the specified timeframe. Retest in the morning if the result is negative but your period is late.
Knowing whether or not that second line appears can be emotional whenever you test. Try relaxation techniques to help sleep, and know that night or morning, a pregnancy test gives accurate results if directions are followed properly.
