Pregnancy tests are designed to react to the pregnancy hormone Human Chorionic Gonadotropin (hCG). This hormone increases if a fertilized egg implants in the woman's uterus. Therefore, an elevated level of hCG in a woman's urine indicates that she is pregnant.
Pregnancy tests have two antibody lines. One is the control line, which turns color when dipped in urine. If the control line appears with color, it confirms that your test is working properly. The other line is called the test line, and this line only turns color if your urine contains the amount of hCG that your pregnancy test is sensitive to.
Today, pregnancy tests are of such high quality that they are more than 99% reliable and accurate from the day of the expected menstruation. However, it is possible to be pregnant even if your pregnancy test is negative. This is especially true if you test before the expected day of menstruation.
The accuracy of early and standard pregnancy tests today is so high that it is extremely rare to encounter a false positive result. If your test is positive – meaning a colored line appears on the test line within the designated timeframe – then you are pregnant.
However, some individuals may still experience menstruation on or a few days after their expected period, leading them to question whether the pregnancy test was a false positive. In most cases, this occurrence is due to a biochemical abortion, which occurs between weeks 3 and 5 of pregnancy. During this period, a pregnancy can only be detected through a pregnancy test or blood test, as a fetal heartbeat would not be visible on an ultrasound scan. Nevertheless, if a colored line appears within the specified time mentioned in the instructions, it indicates an elevated level of hCG, signifying that you are – or were – pregnant.
Please note that there are medications, such as Ovitrelle, that can cause an increase in hCG levels without being pregnant
hCG begins to rise when the fertilized egg implants itself 5-10 days after fertilization by a sperm cell and starts dividing. The level of the pregnancy hormone hCG then increases rapidly and doubles every three days during the first 12 weeks of pregnancy.
Clinical tests have shown that 99% of all pregnant women can test positive on a standard pregnancy test on the day of expected menstruation.
Yes, it is possible to be pregnant even if the pregnancy test is negative. This is especially true if you test before the expected day of menstruation.
The time it takes for a fertilized egg to reach the uterus can vary significantly. It can take anywhere from one day to a week. Since the production of the pregnancy hormone hCG begins when the egg implants in the uterus, there are cases where some individuals may have a positive pregnancy test a week before their expected period, while others may only have a positive test a few days after the expected day of menstruation.