Zenzes M T, Wang P, Casper R F
Department of Obstetrics and Gynaecology, University of Toronto, Ontario, Canada.
Lancet. 1992 Aug 15;340(8816):391-4. doi: 10.1016/0140-6736(92)91471-j.
Many spontaneous abortions are associated with chromosomal abnormality of the fetus. In in-vitro fertilisation (IVF) the chromosome status of untransferred ("spare") embryos and subsequent fate (pregnancy or not) of the transferred sibling embryos might be related. Since the spare and transferred embryos of a patient's cycle genetically are full siblings, the inherited chromosomal abnormalities in spare embryos have a 50% probability of also appearing in transferred embryos. We have tested whether chromosome analysis of spare embryos has predictive power for transferred embryos. 48 couples with a total of 437 embryos were selected because their spare embryos (1-4 per couple; 76 total) were successfully analysed for chromosome status. 16 patients became pregnant. These women produced a higher proportion of chromosomally normal spare embryos (9/24; 37.5%) than those who did not achieve pregnancy (1/52; 1.9%). The proportion of patients who had only normal embryos was significantly higher (p = 0.012) in the pregnant group than in the non-pregnant group, and the proportion of patients who had only abnormal embryos was significantly higher (p = 0.001) in the non-pregnant group. Patients with preclinical and clinical pregnancy losses had only chromosomally abnormal spare embryos; by contrast, 50% of spare embryos from patients with ectopic pregnancies were normal. The proportion of spare embryos that were normal (13%, 10/76), was similar to the livebirth rate of 11% per transferred embryo (19 infants from 171 transferred embryos). These results suggest that chromosome analysis of spare embryos may have predictive value for their transferred sibling embryos. We conclude that improving detection of chromosomally normal embryos for transfer should improve the success rate in IVF.
许多自然流产与胎儿染色体异常有关。在体外受精（IVF）中，未移植（“备用”）胚胎的染色体状态与随后移植的同胞胚胎的命运（是否怀孕）可能相关。由于患者周期中的备用胚胎和移植胚胎在基因上是全同胞，备用胚胎中遗传的染色体异常有50%的概率也会出现在移植胚胎中。我们测试了备用胚胎的染色体分析对移植胚胎是否具有预测能力。选择了48对夫妇，共有437个胚胎，因为他们的备用胚胎（每对夫妇1 - 4个；共76个）成功进行了染色体状态分析。16名患者怀孕。这些女性产生的染色体正常备用胚胎比例（9/24；37.5%）高于未怀孕的女性（1/52；1.9%）。怀孕组中只有正常胚胎的患者比例显著高于未怀孕组（p = 0.012），未怀孕组中只有异常胚胎的患者比例显著高于怀孕组（p = 0.001）。有临床前和临床妊娠丢失的患者只有染色体异常的备用胚胎；相比之下，异位妊娠患者的备用胚胎中有50%是正常的。正常备用胚胎的比例（13%，10/76）与每个移植胚胎11%的活产率相似（171个移植胚胎中有19个婴儿出生）。这些结果表明，备用胚胎的染色体分析对其移植的同胞胚胎可能具有预测价值。我们得出结论，改进对用于移植的染色体正常胚胎的检测应该能提高体外受精的成功率。
