my monthly cycle is very regular from 22nd to 25th of every month the last one was on the 22nd of feb 2011 but on the 5th of march i was involve in a sexual activity could i be pregnant hi, my monthly cycle is very regular, always 22nd to 25th of every month, the last one was on the 22nd of feb 2011, but on the fifth of march, i was involved in a sexual activity, could i be pregnant as today is 22nd of march 2011 and my cycle hasnt started. how ever i took some antibiotic to treat virginal discharge last week, could this also add up to the delay