Whether you’re trying for your first pregnancy or not, taking a pregnancy test can be a tense time. And it’s also normal to have some trouble interpreting the test results.
Here are some tips and information to make reading a pregnancy test result a little easier.
How does a home pregnancy test work?
Home pregnancy tests measure the level of human chorionic gonadotropin (hCG) in urine. This is the same hormone that a health care provider tests for with a blood sample.
HCG is released into the bloodstream by the same cells that will develop into the placenta, which supplies nutrients to the fetus, removes waste products, and performs other vital functions. HCG can be detected by a pregnancy test only after an egg has been fertilized and implanted in the uterus. This usually occurs 6–10 days after ovulation.
Once implantation has occurred, the production of hCG begins and can be detected in blood and urine. The concentration of hCG is initially small, but it will rapidly rise in the days that follow (you can use our online hCG calculator to track your hCG levels at home if it turns out you are pregnant). While serum (blood) testing is much more sensitive than home pregnancy tests (urine tests), urine testing is usually more convenient. Blood tests can detect pregnancy earlier than home pregnancy tests, even before a missed period, but it takes longer to get the results. `
How early will a home pregnancy test be accurate?
In theory, the level of hCG in urine could become high enough to be detected five days before the next period.
Although many tests claim to be up to 99% accurate on the first day of a missed period, research findings suggest that the reliability of these devices is a little uncertain in the earliest stages of pregnancy.
This means that it’s important to be cautious about the results of a very early pregnancy test, particularly if the result is negative. It’s fine to take a pregnancy test early on, but be ready to repeat the test a few days later to confirm the result.
Waiting between a few days and a week after an expected period will provide more reliable results. This is when higher levels of hCG are more easily detected by a home pregnancy test.
How do you take the test?
When it comes to the test, it’s important to take a few precautions. Before opening the packaging, check the expiration date. Storing a home pregnancy test somewhere that’s warm or damp (like the bathroom) can also make it less effective, even if it hasn’t expired yet. These conditions can cause the test to deteriorate in a way that can affect performance and reliability.
It’s best to do the test first thing in the morning when urine is most concentrated. Read the instructions for the specific test carefully. These products may seem very similar to one another, but they differ in how they are used. For the best results, try to follow the directions as closely as possible. Some devices require urination directly onto a testing stick, while others include a dropper to apply the urine to a special testing well.
Interpreting a pregnancy test
Make sure to read the instructions carefully and completely before the test. In the heat of the moment, it can be hard to follow all the steps properly, which could affect the results.
Home pregnancy tests vary widely in how the results are represented on the device. In the early days, most tests had a small window in which a blue or pink line appeared. More recently, the lines have been replaced by a plus or minus sign to represent positive or negative results. The newest digital tests simply read ‘pregnant’ or ‘not pregnant,’ making interpretation very straightforward.
What if the test results produce a very faint line? What does that mean and how should the results be interpreted?
A faint test result could mean that it’s a little too early for the hCG in the urine to be reliably detected by the testing strip. In this particular situation, a faint line probably indicates pregnancy, but repeating the test in a few days’ time will produce more reliable results. By this time, hCG levels will have risen still further and are more likely to be high enough to produce an unambiguously positive test result.
A very faint line may also occur if the urine is too diluted to detect hCG. Drinking a large amount of fluid can dilute the urine and skew the results.
If a faint line becomes a negative test result the second time around, it could be the result of a very early miscarriage in the first few days and weeks of pregnancy. Early miscarriages are a common occurrence and often pass unnoticed.
In such cases, the next period may be heavier than usual, but otherwise there is typically nothing to be concerned about. Most people who experience such early-stage miscarriages and try to get pregnant again go on to have successful, full-term pregnancies.
An ectopic pregnancy or issues with the ovaries might also contribute to misleading test results.
If a home pregnancy test seems to be indicating a false negative or a few home pregnancy tests have returned mixed results, a health care provider can confirm the pregnancy with a blood test or ultrasound.