The effect of fetal gender on the false-positive rate of Down syndrome by maternal serum screening.
OBJECTIVE
(1) To further explore if there is a difference in maternal serum levels of alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG) and estriol (uE3) between fetal genders. (2) To determine if these differences influence false-positive rates of Down syndrome screening in pregnancies with male or female fetuses.


METHODS
This is a descriptive study of women screened at the Ontario Maternal Serum Screening program between 1993 and 1995. The women were grouped by fetal gender and ethnicity. Serum levels of the three markers and screening false-positive rates for Down syndrome were compared between fetal genders in women of different ethnicity respectively.


RESULTS
Complete data were available for 110 306 pregnancies. In all three ethnic groups, MSAFP levels were significantly decreased and MShCG levels were significantly increased in women with female fetuses. The level of MSuE3 was similar between genders. The difference in false-positive rates of Down syndrome between genders was not statistically significant.


CONCLUSIONS
This is the largest study comparing false-positive rates between fetal genders. In contrast to previous studies, the differences in the serum marker levels between fetal genders do not influence the false-positive rates for Down syndrome.
Mueller
V M
VM
Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada. muellevm@mcmaster.ca
Huang
T
T
Summers
A M
AM
Winsor
S H M
SH
D000328:Adult; D044466:Asian People; D044383:Black People; D006063:Chorionic Gonadotropin / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D004964:Estriol / Q000097:blood*; D005189:False Positive Reactions; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D009864:Ontario / Q000453:epidemiology; D011247:Pregnancy; D012727:Sex Characteristics; D044465:White People; D000509:alpha-Fetoproteins / Q000032:analysis*
D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol