Are you Pregnant?

How do pregnancy tests work?

Pregnancy tests look for a special hormone in the urine or blood that is only there when a woman is pregnant. This hormone, human chorionic gonadotropin (hCG), can also be called the pregnancy hormone.

The pregnancy hormone, hCG, is made in your body when a fertilized egg implants in the uterus. This usually happens about 6 days after conception. Although studies show that the embryo does not implant until later in some women. The amount of hCG increases significantly with each passing day you are pregnant.

Many home pregnancy tests claim that they can tell if you are pregnant on the day you expect your period. But a recent study shows that most do not give accurate results this early in pregnancy. Waiting one week after a missed period will usually give a more accurate answer.

Qualitative hCG blood tests just check to see if the pregnancy hormone is present or not. So it gives a yes or no answer. The qualitative hCG blood test is about as accurate as a urine test.

How do you do a home pregnancy test?

There are many different types of home pregnancy tests, or HPTs. Irish pharmacies sell HPTs over-the-counter. They cost between €12 and €20 depending on the brand and how many tests come in the box.

Most popular HPTs work in a similar way. The majority tell the user to hold a stick in the urine stream. Others involve collecting urine in a cup and then dipping the stick into it. At least one brand tells the woman to collect urine in a cup and then put a few drops into a special container with a dropper. Testing the urine first thing in the morning may help increase accuracy.

Then the woman needs to wait a few minutes. Different brands instruct the woman to wait different amounts of time. Once the time has passed, the user should inspect the “result window.” If a line or plus symbol appears, you are pregnant. It does not matter how faint the line is. A line, whether bold or faint, means the result is positive.

Most tests also have a “control indicator” in the result window. This line or symbol shows whether the test is working or not. If the control indicator does not appear, the test is not working properly. You should not rely on any results from a HPT that may be faulty.

Most brands tell users to repeat the test in a few days, no matter what the results. One negative result (especially soon after a missed period) does not always mean you are not pregnant. All HPTs come with written instructions. Most tests also have free phone numbers to call in case of questions about use or results.

How accurate are home pregnancy tests?

Home pregnancy tests (HPTs) can be quite accurate. But the accuracy depends on many things. These include:

  • How you use them – Be sure to follow the directions and check the expiration date.
  • When you use them – The amount of hCG or pregnancy hormone in your urine increases with time. Therefore, the earlier after a missed period you take the test the harder it is to spot the hCG. If you wait one week after a missed period to test, you are more likely to have an accurate result. Also, testing your urine first thing in the morning may boost the accuracy.
  • Who uses them – The amount of hCG in the urine is different for every pregnant woman. Therefore, some women will have accurate results on the day of the missed period while others will need to wait longer.
  • The brand of test – Some home pregnancy tests are more sensitive than others and are better than others at spotting hCG early on.

Many HPTs claim to be 99% accurate on the day you miss your period. But research suggests that most HPTs do not consistently spot pregnancy that early. And when they do, the results are often very faint.

I got a negative result on a home pregnancy test. Might I still be pregnant?

Yes. Most HPTs suggest women take the test again in a few days or a week.

Every woman ovulates at different times in her menstrual cycle. Plus, embryos implant in the uterus at different times. Therefore the accuracy of HPT results varies from woman to woman. Other things can also affect the accuracy.

Sometimes women get false negative results (when the test says you are not pregnant and you are) when they test too early in the pregnancy. Other times, problems with the pregnancy can affect the amount of hCG in the urine.

If your HPT is negative, test yourself again in a few days or a week. If you keep getting a negative result but think you are pregnant, talk with your doctor right away.

Can anything interfere with home pregnancy test results?

Most medicines, over-the-counter and prescription, including birth control pills and antibiotics, should not affect the results of a home pregnancy test. Only medicines that have the pregnancy hormone hCG in them can give a false positive test result. A false positive is when a test says you are pregnant when you are not.

Sometimes medicines containing hCG are used to treat infertility (not being able to get pregnant). Alcohol and illegal drugs do not affect HPT results. But women who may become pregnant should not use these substances.