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Pregnancy tests are designed to detect the hormone human chorionic gonadotropin (hCG). HCG is often called the “pregnancy hormone” because it is produced during pregnancy and is made by cells that form the placenta. Blood tests to detect the hormone are conducted by a doctor, while urine tests can be performed at home with a home pregnancy test (HPT).
Blood tests are slightly more sensitive than urine tests and can detect very small levels of hCG. This allows doctors to get an accurate reading very early on in the pregnancy, about seven to 12 days after conception.
Most clinics will perform a blood test about two weeks after fertility treatment to check the level of hCG. A level of less than 5mIU/ml is considered negative for pregnancy, and anything above 25mIU/ml is considered positive.
In the event that the pregnancy test is positive, the patient will be asked to repeat the blood tests at two- to five-day intervals to check for rising levels of the hormone. In general the hCG level will double every 72 hours. It will reach its peak in the first eight to 11 weeks of pregnancy and then will decline and level off for the remainder of the pregnancy.
In addition to blood tests, an ultrasound will be performed about five weeks after treatment to confirm pregnancy. The scan will verify if the pregnancy is normally located, appears viable and if there is more than one fetus. If you are pregnant, you can follow your Pregnancy Week by Week at JustMommies.com.
Caution must be used when weighing the importance of hCG numbers. A normal pregnancy may initially have low hCG levels and result in a perfectly healthy baby. It is important to direct any questions and concerns to your Ob/Gyn or fertility doctor about your results.
Home Pregnancy Tests (HPTs)
HPTs are inexpensive, private and easy to use. These urine tests can detect pregnancy about two weeks after ovulation. Most drugstores sell HPTs over-the-counter, and prices can range between $8 and $20.
Many HPTs work in a similar way and consist of placing a drop of urine on a prepared chemical strip or placing the strip in the urine stream. The strip is designed to detect the pregnancy hormone.
If an HPT indicates you are pregnant, you should call your Ob/Gyn or fertility doctor right away. He or she can then verify the result.
To learn more about OTC pregnancy tests, read Not All Pregnancy Tests are Equal