Can it happen that beta is negative and a woman carries a child?

To @Ewkaaa: the test for the level of chorionic gonadotropin is very sensitive and specific - it detects the hormone inherent in pregnancy. False negatives can appear if the test is done too early. We do not know about all the cases that have ever occurred in the whole world, but repeated several times negative "beta", made at an appropriate interval from the last intercourse indicates the absence of pregnancy.

So there are no cases in the world that a woman is pregnant and beta from blood done several times is negative?

Up to @Ewkaaa: Beta-hCG levels in pregnancy will always be elevated and will reach values higher than 5 mIU/ml. In a normally developing pregnancy, beta-hCG levels double every 48 hours on average and increase until 9-12 weeks of gestation. At a later stage of pregnancy, it drops to about 10-20% of the maximum value, which can reach up to 280,000 mIU / ml.

Oh dear, I did not notice, and I also have a question whether doing late bete eg 12 weeks after intercourse it will fall to non-pregnancy values, that is, be below 5 ??? Is it always no matter how many days after intercourse, let's assume being pregnant, this hotmon will be elevated?

A similar question has already been asked: https://www.gdziepolek.pl/opinie-i-pytania/98152/czy-sa-na-swiecie-takie-przypadki-ze-beta-jest-cala-ciaze-ujem