title: [Determination of maternal serum alpha-fetoprotein and free beta human chorionic gonadotropin in twin pregnancies comparing to single pregnancies in the second trimester].
authors.forename: Yu
authors.initials: Y
authors.lastname: Jin
authors.forename: Min
authors.initials: M
authors.lastname: Shen
authors.forename: Shi-ming
authors.initials: SM
authors.lastname: Lu
mesh_terms: D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis; D005260:Female; D006801:Humans; D011247:Pregnancy; D059285:Pregnancy, Twin; D011296:Prenatal Diagnosis; D000509:alpha-Fetoproteins / Q000378:metabolism*
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D000509:alpha-Fetoproteins