The absence of vaginal bleeding during the first sexual intercourse may be related to the following factors: first, at an early age, the rupture of the hymen caused by trauma, which one does not know; second, because the hymen is thin, after strenuous exercise, resulting in a hymenal fracture, which one does not notice, so there is no bleeding during intercourse; third, because the hymenal hole is large, there is no bleeding after intercourse The shape of the hymen varies because of individual differences, there are sieve hymen holes, triangular hymen holes, round hymen holes, the vast majority are round, but the size of the hymen holes are different. If the hymenal hole is large enough for the penis to pass through, there will be no bleeding during the first intercourse.