Pregnancy tests: what they are, how they work and how to read the result
How does the pregnancy test work? What is an early pregnancy test? When is the right time to do it and how to interpret the results?
If you’ve had unprotected sex and want to know if you’re pregnant, a pregnancy test is the best way to find out. In this article, we explain everything you need to know about home and non-home pregnancy tests.
Pregnancy tests: when to do them?
Let’s face it right away: any pregnancy test you decide to do will give an invalid result if it is performed on the same day of intercourse or in the first few days thereafter .
To obtain a reliable result , it is necessary to wait for the approach of the cycle and preferably the first day of missed menstruation .
Failure to do so increases the risk of false negatives – this means that the test may not report pregnancy because it was taken too early .
Early pregnancy tests
Early pregnancy tests allow you to detect pregnancy earlier than the more classic models.
Currently, there are urine tests with very high sensitivity on the market that do not require a prescription and can be performed 4-5 days before the expected date for the arrival of menstruation.
In addition, a new blood test has been introduced for some years that does not require a prescription and can be carried out comfortably at home. It is called First to Know and can be performed 7-8 days after presumed fertilization .
Finally, the most precise test of all is the measurement of beta-hCG in the blood , which offers accurate results as early as 6-7 days after presumed conception . It is performed through a simple blood sample and if performed with a medical prescription it is paid for by the National Health Service (SSN) .
Alternative pregnancy tests
Some women use ovulation tests as a pregnancy test . This practice, however, is discouraged. In fact, confirmation of conception can only take place with a real pregnancy test .
How pregnancy tests work
The tests detect the presence of the hormone beta-hCG in the urine or in the blood (depending on the type of test used), which begins to be produced by the precursor of the placenta (the so-called trophoblast) only after the embryo has implanted itself in the ‘uterus .
Since it takes 5-8 days for implantation to occur and a few more days for the hormone to reach detectable quantities in the urine , it is necessary to wait at least 10 days after fertilization for urine pregnancy tests to be able to identify its presence.
Qualitative and quantitative pregnancy tests: what’s the difference?
Pregnancy tests can be divided into qualitative and quantitative.
Qualitative tests simply detect the presence or absence of the hormone beta-hCG in urine or blood and simply give a negative or positive result .
They are qualitative pregnancy tests :
- all urine tests , except digital ones with week indicator
- do-it-yourself blood tests ( First to Know)
- qualitative hCG blood tests performed by blood sampling .
Quantitative tests are more sophisticated and also measure the amount of beta-hCG present in the sample.
Since at the beginning of pregnancy the amount of beta-hCG doubles every 2-3 days , a quantitative test therefore allows us to know the weeks of pregnancy approximately and therefore, with a little approximation, the day of conception .
They are quantitative pregnancy tests :
- digital tests with week indicator
- quantitative hCG tests on blood performed by blood sampling ( beta dosage ).
How to take the pregnancy test
Homemade urine pregnancy test
Indications vary from brand to brand. Therefore, before carrying out the test, it is important to carefully read the instructions and warnings contained in the package, to avoid procedural errors that could distort the results. Also, always check the expiration date .
In general, to carry out the test it is necessary to immerse the absorbent end of the stick for a few seconds in a urine sample , collected in a clean container, or directly under the flow .
For accurate results, it is best to use your first morning urine . Also, avoid drinking too much fluid in the previous two hours , as it could dilute your urine excessively and mask the presence of the beta-hCG hormone.
The test must then be placed on a horizontal surface waiting for it to give the result.
ATTENTION:
1) the control line (C) must be present. Its absence indicates that the pregnancy test is invalid;
2) the result must be read only AFTER the minutes indicated in the instructions have elapsed (generally 3 minutes) and NOT BEYOND the maximum time (generally 10 minutes).
Otherwise you could have false negatives (because the test is read before having detected the beta hCG) or the so-called evaporation line or ghost line (a clear line that appears when the test is not performed correctly and which can be interpreted as a false positive ).
Homemade blood pregnancy test
Self-diagnosis blood pregnancy tests are performed in the same way as tests to control blood sugar in diabetics.
The pack contains a lancing device which is used to obtain a small drop of blood from the fingertip . The leaked blood must be “loaded” on the test. At this point you have to wait 10 minutes to be able to read the result.
Lab test
They are performed on a urine or blood sample .
In the first case, it will be necessary to collect the sample as for a normal urine test and take it to the facility where the test was booked. It would be preferable to use the urine in the early morning, even if it is not strictly necessary.
In the second case, a blood sample will be taken.
In both cases it is not necessary to be fasting.
How to read the result of the t -test
Negative pregnancy test
If the result is negative, the classic tests will show a single line or less, while the digital tests will show a smiley face or the words “not pregnant”.
Positive pregnancy test
If the result is positive, the classic tests will show two colored lines or a + (depending on the type of test) .
Digital tests will show a smiley face or “pregnant” text and the number of weeks since conception (1-2 pregnant, 2-3 pregnant, 3+ pregnant).
In this regard, it is important to remember that by convention, gynecologists do not calculate the weeks of pregnancy and the presumed date of delivery starting from conception, but from the first day of the last menstruation.
Where to buy the pregnancy test and how much it costs
Home urine pregnancy tests
The common urine pregnancy tests can be purchased in pharmacies , some supermarkets or online and do not require any prescription : it is therefore not necessary to go to the family doctor or gynecologist.
The cost ranges from 4 euros upwards , depending on the model and the quantity of sticks contained in the package.
For the choice, the advice is to rely on the pharmacist , who will surely be able to suggest the most suitable one according to the situation.
Home blood pregnancy tests
Home blood tests can be purchased both at pharmacies and online .
They are sold in double packs and cost between 15 and 18 euros, even if offers are available online at significantly reduced prices.
Again, these are self-tests that do not require a prescription .
Blood sampling pregnancy test
They are performed in the hospital or at the analysis laboratories . If performed with a doctor’s prescription, they are paid for by the NHS .
Otherwise, the cost is around 20 euros .
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.