title: Serum human chorionic gonadotropin levels throughout normal pregnancy.
abstract: Human chorionic gonadotropin (hCG) levels were measured in the sera of 443 pregnant women by the beta-hCG radioimmunoassay in order to determine if the third-trimester secondary peak in hCG levels observed by less specific immunoassays was due to cross-reacting substances. hCG was detected as early as six days after presumed conception and peaked between 56 and 68 days, with a nadir at 18 weeks. No secondary rise in hCG levels was demonstrated, indicating that the nonspecific hCG immunoassays give spuriously high values for hCG during the last trimester of pregnancy.
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011863:Radioimmunoassay
chemical_list: D006063:Chorionic Gonadotropin