Most women choose to be tested when they notice a delay in their menstrual period and have reason to believe that they may be pregnant. They then need to choose the method that seems the most reliable in order to meet with their doctor quickly for a pregnancy follow-up or to plan a voluntary interruption of pregnancy (abortion). But then, are all tests equal? Are they all reliable? Are there any precautions to take depending on one’s medical condition?
Demystifying the pregnancy test
Current urine tests detect human chorionic gonadotropin (hCG) in the urine of pregnant women. This hormone indicates the presence of an embryo and its level doubles every 48 hours during the first eight weeks of pregnancy.
Discovered in 1928, hCG has been the subject of much research over the decades to make its detection easier and more affordable. In the 1970s, home tests, which finally became available, met with great success despite their relatively complex handling. No fewer than nine steps were required to obtain a result. However, the autonomy that these tests provided also marked an important leap in women’s liberalization at that time. 
Since the 1990s and the development of new antibodies to the hCG hormone by the diagnostics industry, tests have been simplified and can be used earlier, reaching an efficacy level of about 99%.
Today, experts agree that the best time to take a pregnancy test is within 10 days following a woman’s expected period. This is when the embryo settles in the uterine wall and begins to produce hCG, which is then detectable in the urine and blood.
Different tests, different levels of reliability
“Homemade” pregnancy tests
Many homemade methods abound online: the toothpaste test, needle test, bleach test, salt test, white vinegar test, etc. While their results can be conclusive in some cases, their reliability, on the other hand, has never been scientifically demonstrated. For example, some men who have done these tests for fun have discovered, to their great surprise, that they were “pregnant.”
It should be noted that men can get false positives, even with effective tests. Some testicular cancers produce the same hCG hormone, resulting in a false-positive pregnancy result. Although such pregnancy tests are often performed by men as a joke, the false-positive results they produce can turn out to be true positives for testicular cancer. 
Sometimes, some tests that are considered reliable can still produce false results.
A false negative usually occurs if the test was performed too early, when the hCG hormone is not yet present in a sufficient concentration or if the instructions were not followed correctly. It is recommended that a new test be performed if the absence of menstruation persists or that you consult a doctor if you are unsure.
A false positive, although very rare, is possible in certain situations:
Specific medical treatments capable of distorting the test, generally products used to treat infertility or certain neuroleptics
Recent miscarriage, abortion or delivery resulting in hCG still being present in the body
Certain intestinal cancers or illnesses
Stomach ulcer or cirrhosis
Excessive cannabis use
Contamination with detergent, which can create a chemical reaction and distort the test
In all cases, it is recommended to consult your doctor after a positive result to confirm or invalidate the onset of pregnancy.
What to do after a positive pregnancy test
The various tests available on the market are used to confirm a pregnancy. While urine tests are considered very effective, a blood test is 100% accurate.
In the event of a positive result, it is important to consult health care professionals who will provide a follow-up and support during the pregnancy.
An appropriate medical follow-up will be set up according to the known health conditions and expectations of the mother or parents. This will result in recommendations for certain tests, mainly during the first and second trimesters of pregnancy, among a whole battery of possible tests. The main purpose of these tests is to determine the health of the mother and embryo and to evaluate whether there are any risks of complications or poor fetal development during the pregnancy.
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Urine pregnancy test: A pregnancy test involves measuring the level of beta-hCG, the hormone produced by the placenta in a pregnant woman.
Beta-hCG: hCG (human chorionic gonadotropin) is the pregnancy hormone. This test measures a very specific part of hCG in the blood, namely its beta subunit. The beta-hCG test is used to diagnose and monitor pregnancies, placental diseases and germinal tumours.
Prenatal screening test: Performed during the first trimester of pregnancy, the PreNatest (prenatal screening test) uses a drop of blood to evaluate the risk of carrying a fetus affected by one of the most common birth defects: trisomy 21 (Down syndrome) and trisomy 18 (Edwards syndrome).
First-trimester ultrasound: Provides a more accurate determination of the gestational age of the fetus. The ultrasound is performed between the seventh and ninth weeks of pregnancy.
Nuchal translucency: Provides important medical information such as fetal size, age and health status. It can also detect the presence of twins and diagnose certain birth defects.
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