title: Maternal serum free-beta-chorionic gonadotrophin, pregnancy-associated plasma protein-A and fetal nuchal translucency thickness at 10-13(+6) weeks in relation to co-variables in pregnant Saudi women.
abstract: OBJECTIVE
  To establish normative values and distribution parameters of first-trimester screening markers, namely, fetal nuchal translucency (NT), maternal serum free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A), at 10 to 13(+6) weeks of gestation in Saudi women and to evaluate the effect of co-variables including maternal body weight, gravidity, parity, fetal gender, twin pregnancy, smoking and ethnicity on these markers.
  
  
  METHODS
  A cohort of Saudi women (first cohort n = 1616) with singleton pregnancies prospectively participated in the present study, and fetal NT together with maternal serum free beta-hCG and PAPP-A were determined at 10 to 13(+6) weeks of gestation. The distribution of gestational age-independent multiples of the median (MoM) of the parameters was defined and normative values were established, and correction for maternal body weight was made accordingly. The influence of various co-variables was examined using the data collected from the first and the second (n = 1849) cohorts of women and 62 twin pregnancies, and compared with other studies.
  
  
  RESULTS
  All markers exhibited log-normally distributed MoMs. Gestational age-independent normative values were established. Maternal body weight was corrected, particularly for maternal free beta-hCG and PAPP-A using standard methods. Fetal NT showed a negative relationship with increasing gravidity (r = -0.296) or parity (r = -0.311), whereas both free beta-hCG and PAPP-A exhibited a significant positive relationship. There was a significant increase in the MoM of free beta-hCG in female fetuses. Smoking decreased MoM values of free beta-hCG (by 14.6%; P < 0.01) and PAPP-A (by 18.8%; P < 0.001). Twin pregnancy showed significant increases in MoM values of free beta-hCG (by 1.87-fold) and PAPP-A (by 2.24-fold), with no significant changes in fetal NT MoM values. Fetal NT MoM values were lower in Africans and Asians but higher in Orientals, as compared to Saudi women (P < 0.05; in each case). MoM values (body weight-corrected) of free beta-hCG were 25.2% higher in Africans and 19.4% higher in Orientals but 6.8% lower in other Arabian and Asian (by 5.8%) women as compared to Saudi women (P < 0.05; in each case).
  
  
  CONCLUSIONS
  The normative values and distribution parameters for fetal NT, maternal serum free beta-hCG and PAPP-A were established in Saudi singleton pregnancies, the maternal body weight together with smoking, twin pregnancy and ethnicity being important first-trimester screening co-variables. Gravidity, parity and fetal gender are also considered to influence one or more of the first-trimester markers examined.
authors.affiliation: Department of Clinical Biochemistry, Faculty of Medicine and King Abdulaziz University Hospital, King Abdulaziz University, Jeddah, Saudi Arabia. ardawims@yahoo.com
authors.forename: Mohammed-Salleh M
authors.initials: MS
authors.lastname: Ardawi
authors.forename: Hasan A
authors.initials: HA
authors.lastname: Nasrat
authors.forename: Abdulrahim A
authors.initials: AA
authors.lastname: Rouzi
authors.forename: Mohammed H
authors.initials: MH
authors.lastname: Qari
authors.forename: Mohammed H
authors.initials: MH
authors.lastname: Al-Qahtani
authors.forename: Adel M
authors.initials: AM
authors.lastname: Abuzenadah
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001835:Body Weight; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D016011:Normal Distribution; D048208:Nuchal Translucency Measurement; D011247:Pregnancy / Q000097:blood* / Q000208:ethnology; D011261:Pregnancy Trimester, First; D011272:Pregnancy, Multiple / Q000097:blood; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D012016:Reference Values; D017584:Reproductive History; D012529:Saudi Arabia; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D014427:Twins
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A