Meyers C, Adam R, Dungan J, Prenger V
Department of Obstetrics, Gynecology, University of Maryland, Baltimore, USA.
Obstet Gynecol. 1997 Feb;89(2):248-51. doi: 10.1016/S0029-7844(96)00424-3.
To determine the maternal age at which twin gestations have a risk of fetal aneuploidy comparable to that of singleton pregnancies at maternal age 35, accounting for variation in dizygotic twinning rates by maternal age and race.
Known aneuploidy risks and rates of dizygotic twinning by maternal age and race were used to calculate the risk of fetal aneuploidy at term and in the second trimester by maternal age and race in twin gestations, using previously published calculations.
The risk of at least one aneuploid twin at term is 1/193 at maternal age 31 for both white and African-American women, which is comparable to the risk of 1/192 for an aneuploid singleton term pregnancy at maternal age 35. The risk of at least one aneuploid twin at amniocentesis at maternal age 31 is 1/190 for white and 1/187 for African-American women, which is slightly lower than the rate in singletons of 1/135.
Invasive prenatal diagnosis for detection of fetal aneuploidy should be offered to all women with twin gestations at age 31, regardless of race.
确定双胎妊娠发生胎儿非整倍体风险与35岁单胎妊娠相当的孕妇年龄，同时考虑到不同种族孕妇年龄对双卵双胎发生率的影响。
利用已知的非整倍体风险以及不同种族孕妇年龄的双卵双胎发生率，采用先前发表的计算方法，计算不同种族双胎妊娠孕妇足月及孕中期胎儿非整倍体的风险。
对于白种人和非裔美国女性，31岁时足月至少有一个非整倍体双胎的风险为1/193，这与35岁单胎妊娠非整倍体足月妊娠的风险1/192相当。31岁行羊膜腔穿刺术时，白种人至少有一个非整倍体双胎的风险为1/190，非裔美国女性为1/187，略低于单胎妊娠的1/135。
对于所有31岁双胎妊娠的女性，无论种族如何，均应提供侵入性产前诊断以检测胎儿非整倍体。
