Pregnancy Spotting

i know alot of woman who spot their whole pregnancy and the doctors say its ok…. why do they have this and why is it ok?

The doctors are not sure how far along I am but my last period was Dec. 7th 2007. For the past 4 days ive been having a lot of cramping in both my vaginal and rectual area along with period like cramping. I just found out i was pregnant last night while i was at the er for the pain. They did a ultrasound and said theres no sac or fluid in my tubes ot cause alarm for a etopic pregnancy the sac is forming where it should be. But when i was discharged the doctor told me 1 out of 2 things can be wrong with my baby that i might end up having a etopic pregnancy or 2 im going through a miscariage. He didnt even give my baby a chance to survive. I have 2 other children and have lost 2 other pregnancys i remember with my 2nd son i had cramping but not this bad. Has anyone had cramping during the 1st month or 2 but was still able to carry the baby?? I guess im looking for advice

Ive heard many stories like just a few drops, to full periods thats some doctors classify is spotting.