If it is merely to confirm that you are pregnant, a urine pregnancy tests or home pregnancy test will suffice. If your practitioner has a reason to suspect multiple pregnancy, ectopic pregnancy or a miscarriage, a blood pregnancy test is more often used. Sometimes you will have these blood tests repeated to watch for a rise in the hCG levels. The rate of rise for hCG in pregnancy is that it nearly doubles about every 48 hours, though this can vary and does level off after the second trimester.
See Chart Below
Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Fifth Edition.
Understanding Diagnostic Tests in the Childbearing Year. Frye, A. 6th edition.
hCG Values in Pregnancy
|From Conception||From LMP||mIU/ML or IU/L|
|7 days||3 Weeks||0 - 5|
|14 days||28 days||3 to 426|
|21 days||35 days||18 to 7,340|
|28 days||42 days||1080 to 56,500|
|35 - 42 days||49 - 56 days||7,650 to 229,000|
|43 - 64 days||57 - 78 days||25,700 to 288,000|
|57 - 78 days||79 - 100 days||13,300 to 253,000|
|17-24 weeks||2nd Trimester||4060 to 65,400|
|25 weeks - birth||3rd Trimester||3640 to 117,000|
|Several Days After Baby||-||< 5|