 [ Symptoms ] i took bactrim for a uti while on my period i am on low lowstrine does bactrim affect birth control  recently i have been spotting to the equivalent of a light menstruation i have read that the bleeding during the middle of a cycle could point to pregnancy however i do not recall my boyfriend ejaculating inside of me [ Disease ] no need to worry studies and statistics you read on the internet apply to long term exposure to sulfuric acid mists in the work place and not all studies were conclusive this does not apply to you