Cowans Nicholas J, Stamatopoulou Anastasia, Maiz Nerea, Spencer Kevin, Nicolaides Kypros H
Prenatal Screening Unit, Clinical Biochemistry Department, King George Hospital, Barley Lane, Goodmayes, IG3 8YB, UK.
Prenat Diagn. 2009 Jun;29(6):578-81. doi: 10.1002/pd.2246.
To investigate if fetal sex has an impact on 1st trimester combined screening for aenuploidy.
We studied the first trimester PAPP-A, free beta-human chorionic gonadatropin (beta-hCG) and nuchal translucency levels in 56,024 normal, singleton pregnancies with known fetal sex at birth. We also examined the distributions in 722 pregnancies with trisomy 21 of known fetal sex.
We have found a 14.74% increase in first trimester maternal serum (MS) median free beta-hCG MoM, 6.25% increase of PAPP-A and a 9.41% decrease in delta NT, when the fetus was female. Analysis of data has shown that women carrying a female fetus were 1.084 times more likely to be in the 'at risk' group than those carrying a male fetus. In examining data from 722 pregnancies in which the fetus was affected by trisomy 21, we observed a similar 20.8% increase in free beta-hCG MoM, 5.7% increase in PAPP-A and a 12% decrease in delta NT when the fetus was female. Amongst the trisomy 21 cases, 88.8% of male trisomy 21 cases were detected compared with 91.2% in female cases, this difference was not statistically significant. Correcting for fetal sex redressed the balance in screen-positive rate between the sexes and had a minimal impact on detection rate.
Correcting for fetal sex may be a worthwhile consideration. A cost-benefit analysis would be required to determine if it is feasible to introduce fetal gender assignment into the routine first trimester scan for the purpose of marker correction and whether this would have any significant impact.
探讨胎儿性别是否对孕早期非整倍体联合筛查有影响。
我们研究了56024例出生时胎儿性别已知的正常单胎妊娠的孕早期妊娠相关血浆蛋白A（PAPP-A）、游离β-人绒毛膜促性腺激素（β-hCG）和颈部透明带厚度水平。我们还检查了722例胎儿性别已知的21三体妊娠的分布情况。
我们发现，当胎儿为女性时，孕早期母体血清（MS）中游离β-hCG中位数倍数（MoM）增加14.74%，PAPP-A增加6.25%，颈部透明带厚度差值（delta NT）降低9.41%。数据分析表明，怀有女胎的女性进入“风险”组的可能性是怀有男胎女性的1.084倍。在检查722例胎儿受21三体影响的妊娠数据时，我们观察到当胎儿为女性时，游离β-hCG MoM同样增加20.8%，PAPP-A增加5.7%，delta NT降低12%。在21三体病例中，88.8%的男性21三体病例被检测到，而女性病例为91.2%，这种差异无统计学意义。校正胎儿性别可纠正两性之间筛查阳性率的平衡，且对检测率影响极小。
校正胎儿性别可能是一个值得考虑的问题。需要进行成本效益分析，以确定将胎儿性别判定纳入孕早期常规扫描以校正标志物是否可行，以及这是否会产生任何重大影响。
