Does Taking Ambien Cause Delay In Periods?

I am 21 and I m sexually active but am very careful because I already have a one year old. My SO are very careful condom every time along with me taking my birth control (Ortho tei-cyclen lo) but I ve been taking around two ambiens as needed. I ve been having menstrual cramps but no period this is my week and I m afraid it will surplass. I have taken more then one pregnancy tests and both are negative. Could it be stress or the effect of ambient?