Pregnancy Week by Week

Home Pregnancy Test

Pregnancy tests sold in pharmacies for home use are based on the detection of a pregnancy hormone, called human chorionic gonadotropin (hCG) in the urine of the person tested. Modern pregnancy tests claim that they can detect a pregnancy with more than 99% accuracy from the first day of delayed period, or even four days before the estimated date of the next menstruation. Depending on when fecundation has occurred, pregnancy tests are recommended for use after 10-12 days. The regular menstrual cycle has 28 days and ovulation occurs on the 14 or 15th day, but this is valid only for a small percentage of women, the rest of them having menstrual cycles with many different paTerns.

Human chorionic gonadotropin secreted by the embryo begins to exist immediately after implantation. Initially, it reaches the mother's blood and then the urine. Until the embryo implants itself in the uterus, around 7-10 days (on average) pass, but 12-14 or more can pass in some cases. The egg is released and can theoretically be fertilized within 14 days before the next menstrual period, but many women ovulate later, a week before the next menstrual period, so if their menstruation comes just seven days after fecundation, during which the embryo can be still on the way to the uterus, there is no implantation, so it no chorionic gonadotropin in urine - false negative test result.

If you suspect that the last sexual contact could cause a pregnancy, testing within 10-12 days is unreliable and false negatives are very common. Sperm ceLs live on average three days inside the woman; some may even live for 5 days, so fecundation can happen 5 days after the sexual contact. After fecundation, up to 12-14 days can pass until implantation, then 1-2 days until chorionic gonadotropin in the urine reaches a level high enough to be detected by a home pregnancy tests. So it may take even 21 days after sexual intercourse for the pregnancy to be detected.

When can I do a Pregnancy Test?

The ideal time of pregnancy testing is a week after one's period is delayed or at least 3 weeks after unprotected sex. If you're doing it faster and the result is positive, it means that the embryo was implanted quickly, but if it is negative, this doesn't necessarily mean that there is no pregnancy. Modern pregnancy tests claim they can also detect HCG using any urine, not just the morning one. But because the morning urine is more concentrated, the amount of chorionic gonadotropin is higher, so it is more likely to be detected by pregnancy tests that need a minimum value (depending on brand). Obviously, with the age of pregnancy, the amount of gonadotropin in the urine is higher and can be detected more easily, but if you're in the limit of detectability, it is better to use morning urine. After How long can the Pregnancy Test be Read?

Depending on the brand, each test has a time frame in which to be read for the result to be accurate. In most cases, the reading can be done between 5 to 10 minutes, after 10 minutes any change is not relevant anymore. Find information about this in the prospect or on the packaging of the product.

If in doubt about the outcome of a pregnancy test, the best thing would be to repeat it after 2-3 days. Anyway, in order to clear every doubt, it is best to use 2 tests from the beginning and, if possible, different brands. If all the tests show the same results, then you can be certain about the pregnancy.