Pregnancy test, when to do it, how to do it, and more

If you think you may be pregnant, you can take a pregnancy test to find out for sure. You can do this by consulting your doctor or by purchasing a home pregnancy test kit from a pharmacy or supermarket.

Pregnancy tests detect the concentration in the urine or blood of a hormone called human chorionic gonadotropin (hCG) and also known as the “pregnancy hormone”.

Pregnancy test, after when to do it

The hCG hormone is produced during pregnancy and can be detected as early as 10 days after conception when the fertilized egg attaches itself to the womb. If hCG is present in your blood or urine, it is very likely that you are pregnant.

Pregnancy test, how to do it

You can get tested either at home, with a home pregnancy test that detects hCG in urine, or at your doctor, hospital, or clinic.

Nurses, doctors or specialists confirm a pregnancy with urine or blood tests: the urine tests they use are similar to home tests, while tests that detect hCG in the blood are more sensitive and accurate than urine tests and can detect whether the hormone is present in the blood and how much there is (if the hCG level is very high it could be a sign that you are expecting twins or that you have some ailment).

Urine pregnancy test

Urine pregnancy tests .

Pregnancy test, how it works

Pregnancy test kits base their operation on detecting the concentration of the hormone HCG (human chorionic gonadotropin) or – better – its beta subunit.

HCG is a hormone produced very early in pregnancy (after the fertilized egg implants in the uterus as the placenta begins to develop) and for this reason it is considered a valuable marker   for pregnancy tests.

hCG can be detected in maternal blood as early as eight days after conception. Its level increases daily by about 50% as pregnancy progresses, reaching a peak of about 100,000 mlU/ml at 8-10 weeks. Thereafter its levels decline, and remain stable for the remainder of the pregnancy at approximately 20,000 mIU/mL.

hCG can also be detected with a urine test as its pattern in the urine (not its absolute values) mirrors that in the blood. However, most urine kits only detect if it is present in not too small quantities.

Pregnancy test, when to do it

If you are a sexually active woman of reproductive age, you have a chance of getting pregnant every month.

As for when to get tested,

  • if you have a regular period you should wait for the first day of your period delay;
  • if you have an irregular cycle, you have to wait four to five days after your period is late;
  • otherwise you should wait at least a week or two after intercourse: if you are pregnant, it is necessary to wait seven to twelve days after implantation for your body to start developing detectable levels of hCG.

It is quite clear that if you take the test too soon you run the risk of having a “false negative” result or of being not pregnant when in fact you are.

However, here are some of the signs that may suggest you should take a test.

Missed menstrual cycle

Amenorrhea, or absence of menstruation, is one of the earliest and most reliable signs of pregnancy. Many women have a 28 day menstrual cycle. If this applies to you, consider getting tested when it has been more than a month since your last period.

System losses

Initially in some pregnancies there may be bleeding similar to menstruation: when a woman becomes pregnant, about 10/14 days after conception the blastocyst implants itself in the endometrium, the lining of the uterus, and this can cause the so-called system losses.

To find out more about system leaks,  refer to our in-depth study .

Uterine cramps

The implant can give you sensations similar to menstrual cramps.

Breasts that hurt

In order to support your baby’s growth, your body produces more and more estrogen and progesterone , and these hormones immediately begin to make changes: your breasts may feel tender and appear larger due to increased blood flow; your nipples might hurt, and your breast veins might look darker under the skin.

Nausea, food aversions, stress, frequent urination

These are also the effects produced by the increase in hormones during this time, especially hCG.

Reliability pregnancy test

There are currently no standard criteria for objectively testing, evaluating, and comparing the performance of various urine kit devices.

Many companies claim that their products are highly accurate in detecting conception. A study done in 2014 in Germany on 15 over-the-counter pregnancy kits, however, came to the conclusion that not all of them give results corresponding to what is written in their package inserts: at the time, about 50% of the tests did not have the declared sensitivity.

Even today, home pregnancy tests don’t always have the sensitivity they promise. So those that are described with astonishing claims about their sensitivity and their early detection, should be evaluated with caution as they are unlikely to live up to their claims.

In any case, according to a scientific study, the kits also approved by the FDA (the American Food and Drug Administration) seem to have performances in line with what was declared.

Apart from that, the reliability of the results of the various tests depends not only on the biochemical performance of their systems, but also on how and when they are performed, topics that we will address in the following paragraphs.

To conclude: in verifying conception, urine and saliva tests do not give 100% certain results   6 ] , however the fact remains that, today, even domestic kits have high levels of sensitivity and specificity, levels that are unlikely to be exceeded. Their only “real” alternative is always that of blood sampling: the blood pregnancy test .

Frequent questions

Can a pregnancy test be done in the evening?

Most tests can be done at any time of day, but the best time is definitely in the morning right after waking up. In fact, in this time slot the urine is quite concentrated, and the test will be as reliable as possible.

Can a pregnancy test be done near meals?

Yes, but you should also avoid drinking too much fluid beforehand, as (although this is unlikely to happen) too much fluid dilutes the pregnancy hormone in the urine and could therefore affect the result.

It goes without saying that it is necessary to follow the warnings found on the packaging of the purchased product.

Are home pregnancy tests reliable?

No, home pregnancy tests are not reliable and should never be used as an alternative to   commercially available urine pregnancy tests .

False positives and false negatives

That a possible detection error occurs – almost always – when there is a negative result. In other words, if the result is positive, the margin of error is almost zero; if, on the other hand, it is negative, it could also be possible that a pregnancy is in progress. This could happen, either when the pregnancy test is done too early, or when the kit has been kept in an environment that is too hot or too cold, or when it is used after the expiration date.

The – rare – eventuality of a “false positive” could instead occur when the woman has recently had a baby.

That there are some pathological conditions, such as endocrine tumors and the hydatidiform mole (a mass of abnormal cells that develop in the uterus) which can also “mimic” the hormonal changes detected.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

Leave a Reply

Your email address will not be published. Required fields are marked *