©Pregnancy bliss 2008

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Needless to say, this is an extremely sensitive period of development. Any chemical insults - for example, in the form of drugs/medicines taken during this particular period are likely to have the most profound effect on the fetus.

Pregnancy Tests                                                                                                                                                                                                                                                                                    

 

Urine Pregnancy Test

This is the test that is available almost universally for self-testing. Over the years, the sensitivity of commercially available preg­nancy test kits has improved. Today, it is possible for a urine pregnancy test to confirm a pregnancy within a day of missing a period, which will be about two weeks after conception. Of course, there are still some tests which are not as sensitive and which will only be positive at significantly higher hormone levels. These higher levels may not be reached until ten to fourteen days after the date the period was due.

 

False positive pregnancy test

It is actually possible to have a falsely positive pregnancy test. This also depends on the type of test.

The pregnancy hormone detected in the urine tests is known as hCG. This stands for human chorionic gonadotrophin.

 

· Some less specific test kits have the potential of cross­-reacting with other naturally occurring hormones in the body, and this could lead to a false positive pregnancy test.

· Some infections may also lead to a false positive test.

· The use of some drugs, including penicillin and methadone could also produce a false positive urine pregnancy test.

Most of the latest kits have increased specificity hence the risk of false positive results is greatly minimized.

 

False negative pregnancy test

It is possible, for a variety of reasons, for a pregnant woman to have a false negative test.

The most common cause of a falsely negative test is the use of the older test kits with low sensitivity. Because they need high hormone levels to detect a pregnancy, a test performed too early may turn out negative and probably become positive a week later, when hormone levels are much higher.

The hormone hCG is produced in rapidly increasing quantities soon after implantation. The blood concentration of the hormone doubles roughly every two days and reaches its peak at about nine weeks after conception (eleven weeks of gestation).

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