I have been pregnant 3 times. I was 16 the first time with twins but my then ob told me and my mom I was not pregnant after blood and urine test said negative I had a miscarriage at 4 months. When I was 18 I got pregnant again and I had changed ob due to what had happened so my new ob knew what happened as he saw me for my follow-up after the miscarriage. I went in Aug, Sept, Oct, Nov, and Dec, from Aug to Nov I was told by the doctor and blood and urine pregnancy test that I was not pregnant. In December the doctor did a pelvic exam and said did I tell you that you are pregnant then said let's look at the baby and when he did the u/s he said you are 16 weeks, My son is now a healthy 11 year old, in 2001 I went to the same ob and he said for 3 months I was not pregnant and I had a miscarriage 3 days after my last visit with him. I am now with a knew doctor and I have been having the symptoms since about the end of may and I am again being told that I am not pregnant now if I am I would be 18 weeks last I saw a doctor was July 18 and the test were still negative but the symptoms are getting worse, I also every time have bleed until my 5th to 6th month. I would like to know if you have an idea as to why my test are negative until the 5th or 6th month as even though they knew I was 16 weeks pregnant with my son the test was still negative until my 5th month?