 [ Symptoms ] does sex change our period cycle or could i be pregnant  im not on birth control and have been having sex regularly i had brown spotting and then the next morning bright red period not the usual flow but still quite a bit and its a week early my breasts are tender and i feel extremely bloated i took a pregnancy test a week before was negative but i reckon that was too early i just want to know what i should do [ Disease ] if you are more than a week late starting your period you should take a pregnacy test just to be sure in my experience sex has never changed my cycle except when i was pregnant one of my pregenacies i spotted for only one day which was not normal for me so i took a test to rule that out but it turned out that was the reason why hope this helps