Template:Repeat B-hCG levels

Pregnancy Type	B-hCG Change
Normal	Minimum expected rise depends on initial hCG value:^[1]^[2] Initial hCG <1,500 mIU/mL: minimum 49% rise in 48hrs Initial hCG 1,500-3,000 mIU/mL: minimum 40% rise in 48hrs Initial hCG >3,000 mIU/mL: minimum 33% rise in 48hrs hCG typically doubles approximately every 48-72 hours in early pregnancy Rate of rise slows after hCG reaches approximately 6,000-10,000 mIU/mL
Ectopic	Increases or decreases more slowly than expected ("plateau") Approximately 21% of ectopic pregnancies have a normal hCG rise^[3]
Miscarriage	Expected to decline >21-35% in 48 hrs^[4]

A single hCG level cannot reliably distinguish intrauterine from ectopic pregnancy^[5]
The discriminatory zone (typically 1,500-3,500 mIU/mL depending on institution) is the hCG level above which a gestational sac should be visible on transvaginal ultrasound^[6]

↑ Symptomatic patients with an early viable intrauterine pregnancy: HCG curves redefined. Obstet Gynecol. 2004
104(1)

50-55. PMID 15229000.
↑ Differences in serum human chorionic gonadotropin rise in early pregnancy by race and value at presentation. Obstet Gynecol. 2016
128(3)

504-511. PMID 27500347.
↑ Human chorionic gonadotropin profile for women with ectopic pregnancy. Obstet Gynecol. 2006
107(3)

605-610. PMID 16507930.
↑ Diagnostic criteria for nonviable pregnancy early in the first trimester. N Engl J Med. 2013
369(15)

1443-1451. PMID 24106937.
↑ Diagnosis and treatment of ectopic pregnancy. CMAJ. 2005
173(8)

905-912. PMID 16217116.
↑ Reevaluation of discriminatory and threshold levels for serum beta-hCG in early pregnancy. Obstet Gynecol. 2013
121(1)

65-70. PMID 23262929.