RE: Missed period

Posted By Anna on March 21, 1999 at 11:25:51:







I've been on birth control, namely Lo-Ovral, for approx. 5 years.  My cycles have always been 28 days (even when not on the pill the 5 years prior).  I am now two weeks late (no spotting, etc.).  I took several home pregnancy tests and got a serum pregnancy at one week late - all negative.  When I was due to have my period, I was slightly crampy and since then, I have felt slightly tender.  I have not changed my diet, physical activity or feel that I am stressed.  My doctor did not seemed to be concerned and stated that I continue on the pill.  I did not feel safe starting a new pack fearing that if I were pregnant, that I could possibly endanger the pregnancy.  I took another urine pregnancy test this morning... still negative.  I will be going to a lab this coming week for another serum pregnancy.  What are the chances of being pregnant considering the history of my timely periods?  Is it common to miss a period while on the pill?  I am 23 years old and never been pregnant.
Thank you!