title: No effect of fetal sex on amniotic fluid alpha-fetoprotein.
abstract: OBJECTIVE
  To evaluate the effect of fetal sex on the concentration of amniotic fluid alpha-fetoprotein (AF-AFP) in singletons and twins.
  
  
  METHODS
  Amniocentesis was performed for advanced maternal age between 15 and 20 weeks of gestation. Only patients with normal karyotypes, uncomplicated gestations and normal ultrasound examination were included. AFP was measured in amniotic fluid by RIA and results, expressed as multiples of the median (MoM), were grouped according to fetal sex and were compared by t test.
  
  
  RESULTS
  A total of 603 singleton pregnancies (294 females and 309 males) and 45 twin pregnancies discordant for sex met the inclusion criteria. The mean AF-AFP in singleton males was 1.06 vs. 1.04 MoM in singleton females. In twins, the mean AF-AFP was, respectively, 1.05 and 1.07 MoM (p > 0.05).
  
  
  CONCLUSIONS
  Gender had no impact on AF-AFP in singleton or twin pregnancies, suggesting that the differential influence of sex hormones on the activity of the AFP gene is negligible.
authors.affiliation: Department of Obstetrics and Gynecology, Rambam Medical Center, Haifa, Israel. a_drugan@rambam.health.gov.il
authors.forename: A
authors.initials: A
authors.lastname: Drugan
authors.forename: Y
authors.initials: Y
authors.lastname: Yaron
authors.forename: J
authors.initials: J
authors.lastname: Murphy
authors.forename: S A
authors.initials: SA
authors.lastname: Ebrahim
authors.forename: R L
authors.initials: RL
authors.lastname: Kramer
authors.forename: M P
authors.initials: MP
authors.lastname: Johnson
authors.forename: M I
authors.initials: MI
authors.lastname: Evans
mesh_terms: D000328:Adult; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008423:Maternal Age; D011247:Pregnancy / Q000502:physiology*; D018566:Pregnancy, High-Risk; D011272:Pregnancy, Multiple / Q000502:physiology*; D012727:Sex Characteristics; D014427:Twins; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000509:alpha-Fetoproteins