Is maternal serum triple screening a better predictor of Down syndrome in female than in male fetuses?

The influence of fetal sex in screening for Down syndrome in the second trimester using AFP and free ?-hCG

“…Lockwood et al (1993) studying a cohort of 5114 patients undergoing karyotyping in the 13±22 week period, observed 42 fetuses with Down syndrome. In the 3192 euploid cases with fetal sex outcome, Ghidini et al (1998) in that no statistical difference could be demonstrated, and our larger euploid series shows a somewhat smaller effect than that observed by Bazzett et al (1998) and is in agreement with the 3% lowering observed by Spong et al (1999) in an analysis of 977 cases. The ®nding of a small reduction in maternal serum AFP in euploid female fetuses is consistent with our previous ®nding of a 6% reduction of amniotic uid AFP from pregnancies with a female fetus and our ®nding of no signi®cant difference between sexes in 91 cases of Down syndrome (Spencer et al, 1997).…”

“…In a much larger series of 91 cases (Spencer et al, 1997) this could not be con®rmed, and a 20±30% elevation of total hCG and free b-hCG was observed in the presence of a female fetus but did not reach statistical signi®cance. Bazzett et al (1998), in an analysis of 11 428 euploid patients, showed a 6% elevation of maternal serum total hCG, and Ghidini et al (1998) showed that in 49 cases of Down syndrome maternal serum total hCG was 5% higher in the presence of a female fetus, but again this was not signi®cant. In a small study of 977 euploid pregnancies, the same group (Spong et al, 1999) could demonstrate no signi®cant difference between the sexes for maternal serum total hCG.…”

“…Furthermore, it has been suggested that if this same pattern occurs in cases with Down syndrome the maternal serum screening would be more ef®cient in detecting female affected pregnancies than those with a male affected pregnancy. However, Ghidini et al (1998) could ®nd no evidence for this in reviewing sex ratios amongst cases detected because of abnormal serum screening or those detected because of advanced maternal age. Similarly in this series of Down syndrome cases collected over the past seven years I could show no statistical difference between detection rates in the presence of a female or male fetus.…”

The influence of fetal sex in screening for trisomy 21 by fetal nuchal translucency, maternal serum free ?-hCG and PAPP-A at 10-14 weeks of gestation

“…In the second trimester of pregnancy, screening for trisomy 21 using maternal serum markers such as AFP and free b-hCG or total hCG is well established and although fetal sex has been known for some time to in¯uence maternal serum levels of total hCG (Brody and Carlstrom, 1965) and AFP (Sowers et al, 1983), the implications for trisomy 21 detection rates and false-positive rates have only recently been considered (Bazzett et al, 1998;Ghidini et al, 1998;Spong et al, 1999;Spencer, 2000). Essentially, in the presence of female fetuses, maternal serum total and free b-hCG are increased by some 7% in chromosomally normal fetuses but not signi®cantly different in trisomy 21 fetuses.…”

Fetal gender and maternal serum screening markers

“…Although results from several studies have suggested that fetal gender may have an effect on the maternal serum concentration of pregnancy-related products, [1][2][3][4][5][6][7][8] we could not find a controlled study in which clinical confounding variables that may affect the concentration of maternal serum screening markers for chromosomal and pregnancy complications had been excluded from analysis before the evaluation of the possible effect of fetal gender. For this reason, we performed a nested study in which the clinical records of 213 pregnant women who had consented to donate blood for biochemical research purposes during pregnancy were reviewed in a protocol approved by the institutional review board of Texas Tech University.…”