If the second line on the test is barely noticeable, then this may indicate both a false positive result (there is no pregnancy, but the test will determine it) and a false negative result (there is pregnancy, but the test does not recognize it).
Possible reasons for incorrect operation of the device are as follows:
• The woman is pregnant but is testing too early. In this case, the content of chorionic gonadotropin in the urine does not reach the level necessary for the test to fully respond.
• The test itself was of poor quality. A weak line on it may appear when the device is expired, defective or stored incorrectly. A woman should be especially wary when both bands turn out to be blurry or weak. There may be spots on the test or the formation of a strip in the wrong place - all these are signs of damage to the device.
• The sensitivity of the test has a low threshold. The result will be more reliable, the higher the sensitivity of the test to hCG. Modern devices are able to capture the hormone in the urine, starting from 10 mIU / ml. The most “unreliable” in this regard are the inexpensive strip tests, which have a sensitivity of 25 mIU / ml and often give a dubious result in the early diagnosis of pregnancy.
• Too much or too little urine was included in the test. If the test in urine is overexposed, then this can lead to the fact that the reagent simply spreads over the strip, and it will be fuzzy. When a woman does not withstand the urine test for the prescribed time, this will ensure that the hCG hormone is not enough to completely stain the second strip.
• Unstable menstrual schedule. In the event that a woman’s monthly cycle is unstable, she may conduct a study too early, which means that hCG in the urine will not be enough to get a clear result.
• Late onset of pregnancy. This reason is also associated with too early research. Sometimes it happens that ovulation is somewhat late. As a result, the fertilization of the egg does not occur in the middle of the cycle, but closer to its end. Naturally, menstruation does not occur, but chorionic gonadotropin in the urine is still not enough for the test to be able to “examine” it well.
• Recent abortion. If a woman had an abortion a few weeks ago, chorionic gonadotropin continues to circulate in her body. Gradually, its level decreases, but a sharp decline cannot occur. Therefore, a test performed 4-30 days after an abortion will produce a weak second strip, although in fact there is no pregnancy.
• Taking drugs with hCG. Some medicines contain human chorionic gonadotropin, for example, infertility pills (Pregnil, Profazi, Novarel and others). Even after the end of the therapeutic course, their components may linger in the body for some time and lead to the appearance of a weak second strip on the test.
• Trophoblastic diseases, such as uterine chorionepithelioma, increase the level of hCG in the blood and urine, which can cause a pale line to appear on the test, despite the absence of an embryo. Sometimes such a result can be obtained with uterine fibroids, ovarian cysts or mole.
• The presence of an ectopic pregnancy. Often it is with an ectopic pregnancy that the second band on the test appears weakly. The body produces chorionic gonadotropin, but in insufficient volume, so the device cannot give an adequate response.
• Frozen pregnancy. In this case, the woman's embryo is stored in the uterine cavity, but it has stopped its development. Accordingly, the rate of hormone production falls, which can lead to the appearance of a weak strip on the test. A woman should be alerted by such signs as pain in the lower abdomen, the appearance of spotting, lack of menstruation, fever.
• Climax. Sometimes during menopause, against the background of hormonal failure, a woman's level of chorionic gonadotropin in the blood and urine increases. This may cause the test result to be questionable.
• Diseases of the kidneys. If a woman has severe impairments in the functioning of the kidneys, then this may lead to the fact that hCG in the urine will not be excreted in sufficient volumes. Therefore, the test in this case often reacts to the presence of pregnancy with a weak second band.
Test manufacturers note that the presence of a weak band on the test should be considered a positive result.
However, it is still recommended to conduct a control study using a new pregnancy test. It is best to do this after a few days. If the second test produces a bright and clear line, then the result can be safely considered positive. When the strip on the test is again weak or blurry, you should seek the advice of a specialist. After all, often such test results can indicate health problems.