Nov 27, 2012
Testing for pregnancy is a very exciting time for expecting mothers. Blood test is a sure way to find out whether you are pregnant or not. But under what circumstances can it go wrong?
Blood tests for pregnancy measure the formation of human chorionic gonadotropin (hCG) to base their results. They are generally more reliable than home pregnancy tests which measure the same hormone but cannot detect little traces of it found during first 4 weeks of conception.
Blood tests detect pregnancy about 7 to 12 days after conception and they can also determine the concentration of the hormone hCG in your blood. This information is useful for your health care provider as it helps him to track some of your problems. If you feel having symptoms of pregnancy such as missing a period, pelvic pain, breast tenderness, irregular spotting or vomiting, getting a pregnancy blood test is recommended for confirming pregnancy or ruling it out.
A blood test may not detect human chorionic gonadotropin (hCG) if the test is done during the earliest part of pregnancy. As already stated, it takes at least 7 days after conception for a pregnancy blood test to show positive, but there are some cases in which the production of hCG in women gets delayed. Most of the times though, after missing the first period, test will report positive if the woman is pregnant.
A normal pregnancy shows typical levels of hCG over time. In pregnant woman the level of human chorionic gonadotropin (hCG) increases right through the first trimester, and gradual decrease is reported over time. During the first trimester, a woman may need to get this test done repeatedly to gauge the level of its rise. Very low rise in the level of hCG is considered a bad sign for pregnancy.
The accuracy of home pregnancy tests is considered to be 97% if performed correctly. Though a blood pregnancy test is more accurate but it need not be more sensitive. The method, technique and laboratory equipments have a lot of bearing on the results. Other than the case of testing for pregnancy too early, some other causes of blood pregnancy tests being wrong are much more obscure. It just so happens with some women that they do not produce enough hCG even after showing all signs and symptoms of pregnancy.
At times, it seems rather inane when one finds a woman with a big protruding belly giving a negative in the pregnancy test. Other than a few such once in a blue moon cases, you can have reasonable expectation of getting accurate result if you do not perform the blood test for pregnancy too early of course.
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