The pregnancy test

Last time we talked about pregnancy signs and symptoms and left off with taking a home pregnancy test.  A missed menstrual cycle is the most common symptom leading a woman to take a pregnancy test.  Taking a pregnancy test can be filled with excitement for some people, whereas for others it may be a little intimidating.  No matter how you feel about the idea of being pregnant, a pregnancy test may let you know, one way or the other, if you are pregnant.

How does a test tell if you are pregnant or not?

A pregnancy test detects the presence of a hormone called human chorionic gonadotropin (hCG) in your blood or in your urine. hCG is produced in the placenta shortly after the embryo attaches to the uterine lining and builds up rapidly in your body in the first few days of pregnancy.

Choosing a home pregnancy test

There are a lot of home pregnancy tests out there.  Two of the most recognized name brands on the market are the Clearblue pregnancy test and the First Response pregnancy test.  Beyond these you have lesser known brands and even no name bargain pregnancy tests offered at the dollar store of all places.  In the end the choice is yours and you have to strip away all the fancy claims and focus group tested names to get the test that meets your needs.  Grab 5 different brands regardless of price and they will all claim a 99% accuracy rating. All this 99% means is that when the test is administered perfectly the results are correct 99% of the time, and truthfully, you only get the 99% accuracy rating if you wait until after your period is late.

There are tests which boast the ability to read pregnancy as early as one week before you are late, however, reading the fine print will bring your baby dreams down to earth with an unpleasant bump.  The reality is, predicting pregnancy this early, even with the tests with specialize in early detection, will only give you an accurate reading rate in the 60% range.  That is only slightly better than half, so you still really don’t know for sure and certain. Which means you will find yourself testing again in a week when your period is late.

My advice:  When choosing a home pregnancy test, don’t focus so much on early detection, or the accuracy rating of 99% shared by every test on the market.  Instead, focus on following the directions of the test down to the tiniest of details to get your most accurate results.

How long do I have to wait before I take a test?

Most doctors recommend that you wait until the first day of your missed period before taking a home pregnancy test. A missed period is usually one of the first signs of pregnancy.   This is usually around two weeks after conception.

A blood test administered by your doctor is more sensitive than the early home tests and can be taken between seven and twelve days after you conceive.  It is possible that these tests can be done  too early and show a false negative result.  If you receive a negative result and still do not start your period, another test should be repeated.

How accurate are home tests?

Home tests are pretty darn accurate when used correctly.  We’re talking about a 97% accuracy.  However, there’s still a 3% margin of inaccuracy.  Part of that can be chopped up to human error or testing too soon.  The other part of that 3% fall into the false-positve category, and we’ll talk about that.

If you take a test too early, you may get a false negative (when the test says you are not pregnant but you are). Your body needs time for the hormone to rise to a high enough level to be detected in a test. If the test comes back negative but you still think you could be pregnant, wait a few days and test again.  And if you still get a negative test and suspect you’re pregnant, make an appointment to see your doctor.  While home pregnancy tests are quite accurate, there are factors that can give you negative results even when you’re pregnant, such as:

• The test is past its expiration date.
• You took the test the wrong way.
• You tested too soon.
• Your urine is too diluted because you consumed large amounts of fluid right before the test.
• You are taking certain medications, such as diuretics or antihistamines.

Again, if you get two negative tests but suspect you are pregnant, make an appointment with you doctor for a blood test.  Blood tests are done at your doctor’s office, but are used less often than urine tests. These tests can detect pregnancy earlier than a home pregnancy test, or about six to eight days after ovulation. But with these tests, it takes longer to get the results than with a home pregnancy test.Two types of blood pregnancy tests are available:A qualitative hCG test simply checks to see if hCG is present. It gives a “yes” or “no” answer to the question, “Are you pregnant?” Doctors often order these tests to confirm pregnancy as early as 10 days after a missed period. However, some of these tests can detect hCG much earlier.

A quantitative hCG test (beta hCG) measures the exact amount of hCG in your blood. It can find even very low levels of hCG. Because these pregnancy tests can measure the concentration of hCG, they may be helpful in tracking any problems during pregnancy. They may also be used to rule out a tubal (ectopic) pregnancy or to monitor a woman after a miscarriage when hCG levels fall rapidly.

Back to the home pregnancy test.  Very rarely, you can test positive for a pregnancy when you actually are not pregnant.  False positives (when the test says you’re pregnant but you’re not) are possible, but rare. A positive pregnancy test is a pretty good indication that you are pregnant.   Again, false-positive results are very rare, but they can happen.  A false-positive means you’re not pregnant but the test says you are. You could have a false-positive result if blood or protein is present in your urine. And certain medications, such as tranquilizers, anti-convulsants, or hypnotics, may also cause false-positive results.

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