How Pregnancy Tests Work
There is a specific hormone called human chorionic gonadotropin, also known as hCG, that is only present in the urine or blood of a woman who is pregnant. When a fertilized egg is implanted in the uterus, this pregnancy hormone is produced. For most women, this process usually occurs about six days after the egg and sperm unite. However, studies have shown that, for up to ten percent of women, implantation does not happen until a much later time. It may not even happen until well after the first day of a woman’s missed period. As pregnancy progresses, the levels of hCG build up progressively in the body and it continues to do so throughout the pregnancy.
The Different Kinds Of Pregnancy Tests
1. Blood Tests That Detect Pregnancy
A doctor can analyze a blood sample and determine if the hormone hCG is present. This method is often preferred because it can detect levels of hCG in earlier stages of pregnancy than urine tests can. There are two types of blood tests that a doctor can perform to test for pregnancy. The first is a quantitative blood test, also called a beta hCG test. This type of test can reveal the exact amount of the hormone hCG that is in the blood. Even the smallest amounts can be detected through this test making it extremely accurate. The second type of blood test is a qualitative hCG blood test that reveals simply a yes or no answer as to whether that hormone is there in the blood at all. Less preferred over the quantitative test, is similar to a urine test when it comes to accuracy.
2. Urine Tests That Detect Pregnancy
Often preferred by women because they can be done in the privacy of one’s home, a urine pregnancy test can be used to detect if the hCG hormone is present in the urine stream. This method for detecting pregnancy is inexpensive and easy to use. If performed at the right time and used correctly, urine tests can be very accurate. They can let a woman know as early as one week after a missed period if she is pregnant.
How To Take A Home Pregnancy Test
Women have many choices when it comes to home pregnancy tests, also known as HPTs. They can be found at most drugstores and are sold over the counter at a relatively inexpensive price. Price points can vary depending on the brand of home pregnancy test and the number of tests that are included in the box.
Regardless of the brand, most HPTs work about the same way. The user is instructed to either hold the pregnancy test stick in the urine stream, or collect urine in a cup and distribute a few drops into a special container. Then, the user has to wait for a specified length of time as indicated for each test. Lastly, she can look at the “results window” and match what she sees to the description of results found in the instructions. For example, some tests will show a plus sign, a line, or the word “pregnant” if the test comes back positive. Many HPTs have a “control indicator” that reveals a line or other symbol to show that the test is working properly.
Women should not trust a result from a HPT that may not be in working order. Most HPT makers will instruct women to repeat the test after a few days have passed, regardless of how accurate the results look after the first try. They caution that one negative test result does not always mean that a woman is not pregnant, especially if the test is taken right after a missed period. Regardless of the brand, all HPTs will include written instructions, and most also have a toll-free phone number should the user need additional assistance.
The Accuracy Of Home Pregnancy Tests
Several factors determine the accuracy of home pregnancy tests. Firstly, the user should check the expiration date and then proceed to follow the instructions step by step. In general, waiting the full ten minutes after taking the test before trying to interpret the results is the best way to get an accurate reading. Secondly, since a home pregnancy test gives a yes or no answer as to whether or not the hCG hormone is present, the longer you wait after a missed period, the more apt the test is to detect this hormone that increases as pregnancy progresses. Even though many HPTs claim accuracy on the first day after a missed period, research suggests that waiting a week will assure a more definitive result. Until then, the test may not pick up on the traces of hCG that are present. It is also recommended that the test be taken in the morning for the most accurate results. Thirdly, the accuracy of a home pregnancy test will vary from woman to woman. This is so because women ovulate at different times during the menstrual cycle. In addition, the hCG hormone is only produced once implantation has occurred. Therefore, for those women who do not experience implantation early on, a test taken on the first day of a missed period will not be accurate. Lastly, the brand of HPT does matter. Some are just better at detecting trace levels of hCG.
When to Take A Home Pregnancy Test To Get An Accurate Result
If you need to know if you are pregnant sooner than a week after your missed period, it is highly recommended that you go to your doctor for a blood test. Even though most HPTs claim that they can detect pregnancy the day after a missed period, the results of tests taken that soon are often inconclusive or misunderstood. Waiting a full week after a missed period to take a urine pregnancy test is the best way to ensure that it will give an accurate result.
What To Do Next If A Home Pregnancy Test Says You Are Pregnant
The first thing you should do if a home pregnancy test comes back positive, indicating that you are indeed pregnant, is call your doctor. He or she will be able to order a more sensitive test to ensure the results of your home test were accurate. Plus, your doctor can also do a pelvic exam. Visiting your doctor as soon as you discover you are pregnant is the first step you can take to make sure that you and your baby will remain healthy.
Why You May Be Pregnant Even If A Home Pregnancy Test Says You Are Not
Most home pregnancy tests will instruct women to retake the test in a few days if the first result comes back negative. This is because it is possible that you can be pregnant even if the fist test you take doesn‘t show it. Because women ovulate at different times during the menstrual cycle and some women do not experience implantation for a week after a missed period, a test taken on the first day of a missed period may not be accurate. It is different for every woman. Other factors can influence the accuracy of a home pregnancy test as well. Not only can taking the test too early on in your pregnancy produce a false positive, there may also be problems with the test itself. No matter how many home pregnancy tests you take, if they come back negative and you still feel like you may be pregnant, you should see your doctor immediately.
Things That May Affect A Home Pregnancy Test
Very few medications, either prescription or over the counter, affect the results of a home pregnancy test. Similarly, alcohol and illegal drugs also do not have an effect on HPTs. That said, those who are trying to become pregnant or could become pregnant should not use these substances. While birth control pills and antibiotics have no impact on the results of an HPT, those medicines that contain the pregnancy hormone hCG can produce a false positive. A false positive is when a home pregnancy test reveals that you are pregnant but you really are not. Those women who are not able to become pregnant naturally and take infertility medicines containing hCG may get a false positive result from a HPT.Read more: