Women are often anxious when choosing the most reliable early pregnancy test. A healthy mom and baby are important, even during the first few weeks. In the past, early pregnancy tests were not available, but today a woman can find out she is pregnant within 10 days of conception.
Blood Tests
A blood test is the earliest, most reliable method to detect a pregnancy. It can detect a pregnancy seven to 12 days after conception by measuring the amount of human chorionic gonadotropin, or hCG, in the bloodstream. A woman will begin producing this hormone at the time the fertilized egg implants in the uterus. The hormone increases in concentration over the next eight to 10 weeks.
A pregnancy blood test can be quantitative, meaning it can measure the concentration of hCG in the blood. It can also be qualitative, providing a positive or negative result.
In 2001, doctors at Henry Ford Hospital presented their study to the American College of Emergency Physicians: Of 662 women who were given both urine and blood tests to detect pregnancy, researchers found 5.9 percent of false negatives within the urine test group, thereby concluding that blood tests were more accurate than urine tests.
Urine Tests
The second most accurate and reliable early pregnancy test is a urine test. Most of these tests can be used at home. They measure the amount of hCG in the urine. Some tests are more sensitive, in that they can detect hCG at a much lower concentration. The more sensitive the test, the earlier it can be used after conception. According to the American Pregnancy Association, urine tests are 97 percent accurate when done correctly.
Studies at the University of New Mexico School of Medicine in 2003 found that First Response Early Result Pregnancy Test was the most sensitive among 18 brands. The school reported in the "American Journal of Obstetrics and Gynecology" that this test could detect concentrations of hCG as low as 12.5 mIU/ml. Most other tests required at least 25 mIU/ml to detect pregnancy. The manufacturer of First Response Early Result claims the test can be used six days before a woman's missed period. The second most sensitive test in this study was the Clearblue Easy home pregnancy test.
Digital Home Tests
Digital tests are home pregnancy tests that use words instead of lines to show the results. Traditional tests use pink or blue lines to show the presence of hCG in the urine. In 2003, Clearblue Easy received approval from the United States FDA to market a digital test. In this test, the results are read as "pregnant" or "not pregnant," instead of the pink or blue lines.
A study in 2008, reported in "Current Medical Research and Opinion," compared Clearblue Easy Digital to five other non-digital tests and found that volunteers read the digital test with 100 percent accuracy compared to the traditional blue and pink line tests.
Timing
Timing is a critical factor in the accuracy and reliability of detecting pregnancy. A woman may not know exactly when ovulation and conception occurred, and in trying to get the earliest results she may take a test one day too early. The hCG becomes detectable as it increases in concentration. These levels increase rapidly, doubling every 24 to 48 hours. If a test shows a negative result and it is still early in a woman's cycle, the test should be repeated in a day or two.
Considerations
Each woman is different and the rate and amount of hCG that she will produce upon conception will be unique. Sometimes a home test taken too early may show a negative pregnancy, when actually the amount of hCG in the urine may be too low for that woman. Blood tests can be administered too early as well. It is important that women who have health problems work with a doctor and get an accurate test result. Health care for the mom and baby can then begin early.
References
- Doctor's Guide Publishing: ACEP: Urine hCG Tests May Miss Early Pregnancy
- Baby Hopes: Is A Blood Test For Pregnancy More Accurate Than A Urine Test?
- "American Journal of Obstetrics and Gynecology": Accuracy of Home Pregnancy Tests at the Time of Missed Menses
- American Pregnancy Assoication: Understanding Pregnancy Tests: Urine & Blood
- "Current Medical Reserach & Opinion": Comparison of Accuracy and Certainty of Results of Six Home Pregnancy Tests Available Over-the-Counter
